Workaround: create a custom RadListFilterPopup
private void radGridView1_FilterPopupRequired(object sender, FilterPopupRequiredEventArgs e)
{
    e.FilterPopup = new MyRadListFilterPopup(e.Column);
}

public class MyRadListFilterPopup : RadListFilterPopup
{
    public MyRadListFilterPopup(GridViewDataColumn dataColumn)
        : base(dataColumn, false)
    { }

    protected override RadListFilterDistinctValuesTable GetDistinctValuesTable()
    {
        if (this.DataColumn.OwnerTemplate.HierarchyLevel == 0)
        {
            return base.GetDistinctValuesTable();    
        }

        GridViewColumnValuesCollection distinctValues = this.GetDistinctValuesWithFilter(this.DataColumn);
        RadListFilterDistinctValuesTable valuesTable = new RadListFilterDistinctValuesTable();
        valuesTable.FormatString = this.DataColumn.FormatString;
        valuesTable.DataConversionInfoProvider = this.DataColumn;

        GridViewComboBoxColumn comboBoxColumn = this.DataColumn as GridViewComboBoxColumn;
        if (comboBoxColumn != null && !String.IsNullOrEmpty(comboBoxColumn.ValueMember))
        {
            foreach (object value in distinctValues)
            {
                if (value != null && value != System.DBNull.Value)
                {
                    object rowValue = value;
                    object lookupValue = ((GridViewComboBoxColumn)this.DataColumn).GetLookupValue(value);

                    if (comboBoxColumn.FilteringMode == GridViewFilteringMode.DisplayMember)
                    {
                        rowValue = lookupValue;
                    }

                    if (lookupValue != null)
                    {
                        valuesTable.Add(lookupValue.ToString(), rowValue);
                    }
                }
            }
        }
        else
        {
            foreach (object value in distinctValues)
            {
                valuesTable.Add(value);
            }
        }

        return valuesTable;
    }

    private GridViewColumnValuesCollection GetDistinctValuesWithFilter(GridViewDataColumn column)
    {
        GridViewColumnValuesCollection distinctValues = new GridViewColumnValuesCollection();
        int count = column.OwnerTemplate.ExcelFilteredColumns.Count;
        if ((count > 0 &&
            column == column.OwnerTemplate.ExcelFilteredColumns[count - 1]) || column.OwnerTemplate.HierarchyLevel > 0)
        {
            if (count == 1 || column.OwnerTemplate.HierarchyLevel > 0)
            {
                int index = column.Index;
                if (index >= 0)
                {
                    IList<GridViewRowInfo> templateRows = column.OwnerTemplate.Rows;
                    if (templateRows.Count == 0 && column.OwnerTemplate.Parent != null && column.OwnerTemplate.HierarchyLevel > 0)
                    {
                        templateRows = new List<GridViewRowInfo>();
                        GridViewInfo templateViewInfo = column.OwnerTemplate.MasterViewInfo;
                        for (int i = 0; i < column.OwnerTemplate.Parent.Rows.Count; i++)
                        {
                            GridViewRowInfo parentRow = column.OwnerTemplate.Parent.Rows[i];
                            ((List<GridViewRowInfo>)templateRows).AddRange(column.OwnerTemplate.HierarchyDataProvider.GetChildRows(parentRow, templateViewInfo));
                        }
                    }
                    
                    foreach (GridViewRowInfo row in templateRows)
                    {
                        object cellValue = row.Cells[index].Value;
                        if (!distinctValues.Contains(cellValue))
                        {
                            distinctValues.Add(cellValue);
                        }
                    }
                    if (distinctValues.Count > 0)
                    {
                        return distinctValues;
                    }
                }
            }
        }

        return distinctValues;
    }
}

Workaround: create a custom GridDetailViewCellElement
Public Class Form1
    Sub New()

        InitializeComponent()

        AddHandler dgvPatients.CreateCell, AddressOf dgvPatients_CreateCell

    End Sub

    Private Sub dgvPatients_CreateCell(sender As Object, e As GridViewCreateCellEventArgs)
        If e.CellType = GetType(GridDetailViewCellElement) Then
            e.CellElement = New MyGridDetailViewCellElement(e.Column, e.Row)
        End If
    End Sub

End Class

Public Class MyGridDetailViewCellElement
    Inherits GridDetailViewCellElement

    Sub New(column As GridViewColumn, rowElement As GridRowElement)
        MyBase.New(column, rowElement)
    End Sub

    Public Overrides Sub UpdateTabItemsVisibility()
        If Me.DetailsRow Is Nothing Then
            Return
        End If

        MyBase.UpdateTabItemsVisibility()
    End Sub

End Class

To reproduce: populate a grid and enable multiple selection. Use cell selection. When you click the row header, the entire row (all cells from the row) is selected no matter the SelectionMode. However, if you start a selection from the row header and move the cursor, only the cells from the first column get selected. The attached gif file illustrates the behavior.  The expected behavior is that all cells from the affected columns should be selected when starting the selection from the row header.

Workaround:

Sub New()
    InitializeComponent()
    Me.RadGridView1.MultiSelect = True
    Me.RadGridView1.SelectionMode = Telerik.WinControls.UI.GridViewSelectionMode.CellSelect

    AddHandler Me.RadGridView1.MouseDown, AddressOf GridMouseDown
    AddHandler Me.RadGridView1.MouseUp, AddressOf GridMouseUp
    AddHandler Me.RadGridView1.MouseMove, AddressOf GridMouseMove
End Sub

Dim isMouseDown = False
Dim startRow As GridViewRowInfo
Dim lastHoveredCell As GridCellElement
Private Sub GridMouseDown(sender As Object, e As MouseEventArgs)
    Dim cell As GridRowHeaderCellElement = TryCast(Me.RadGridView1.ElementTree.GetElementAtPoint(e.Location), GridRowHeaderCellElement)
    If cell IsNot Nothing Then
        isMouseDown = True
        startRow = cell.RowInfo
    End If
End Sub

Private Sub GridMouseUp(sender As Object, e As MouseEventArgs)
    isMouseDown = False
    startRow = Nothing
End Sub

Private Sub GridMouseMove(sender As Object, e As MouseEventArgs)
    If isMouseDown Then 
        Dim cellUnderMouse As GridCellElement = TryCast(Me.RadGridView1.ElementTree.GetElementAtPoint(e.Location), GridCellElement)
        If cellUnderMouse IsNot Nothing AndAlso Not cellUnderMouse.Equals(lastHoveredCell) Then
            lastHoveredCell = cellUnderMouse
            Me.RadGridView1.ClearSelection()
            Me.RadGridView1.SelectedCells.BeginUpdate()
            If startRow.Index > cellUnderMouse.RowInfo.Index Then
                For index = cellUnderMouse.RowInfo.Index To startRow.Index
                    Me.RadGridView1.Rows(index).IsSelected = True
                Next
            Else
                For index = startRow.Index To cellUnderMouse.RowInfo.Index
                    For Each cell As GridViewCellInfo In Me.RadGridView1.Rows(index).Cells
                        cell.IsSelected = True
                    Next
                Next
            End If
            Me.RadGridView1.SelectedCells.EndUpdate(True)
        End If
    End If
End Sub

The behavior should be consistent no matter if you change the current column or the current row.

Please refer to the attached sample project which result is illustrated in the provided screenshot.

Workaround:
this.radGridView1.ClearSelection();
this.radGridView1.CurrentRow = null; 
this.radGridView1.Rows[1].Cells[2].IsSelected = true;

Please refer to the attached sample project and select a new value in the drop down.

Workaround: change the PageSize in the RadDropDownListElement.PopupClosed event:

public sealed class PageSizeDropdownHeaderCellElement : GridHeaderCellElement
{
    public PageSizeDropdownHeaderCellElement(GridViewColumn col, GridRowElement row) : base(col, row)
    {
        TextAlignment = ContentAlignment.TopCenter;
        Alignment = ContentAlignment.TopCenter;
    }

    private RadDropDownListElement _dropDownListElement;

    protected override void CreateChildElements()
    {
        base.CreateChildElements();
        _dropDownListElement = new RadDropDownListElement();
        if (_dropDownListElement != null && _dropDownListElement.DataSource == null)
        {
            _dropDownListElement = new RadDropDownListElement();
            _dropDownListElement.BindingContext = new BindingContext();
            _dropDownListElement.DropDownStyle = Telerik.WinControls.RadDropDownStyle.DropDownList;

            _dropDownListElement.Items.Clear();
            _dropDownListElement.Items.Add(new RadListDataItem("10", 10) { Selected = true });
            _dropDownListElement.Items.Add(new RadListDataItem("25", 25));
            _dropDownListElement.Items.Add(new RadListDataItem("50", 50));
            _dropDownListElement.Items.Add(new RadListDataItem("100", 100));
            _dropDownListElement.Items.Add(new RadListDataItem("All", -1));

            _dropDownListElement.Margin = new Padding(15, 0, 0, 0);
            _dropDownListElement.StretchHorizontally = true;
            _dropDownListElement.NotifyParentOnMouseInput = false;
            _dropDownListElement.Popup.MouseClick += Popup_MouseClick;
            _dropDownListElement.PopupClosed += _dropDownListElement_PopupClosed; 
            this.Children.Add(_dropDownListElement);
        }
    }

    RadListVisualItem elementUnderMouse;

    private void Popup_MouseClick(object sender, MouseEventArgs e)
    {
        elementUnderMouse = _dropDownListElement.Popup.ElementTree.GetElementAtPoint(e.Location) as RadListVisualItem;
    }
    
    private void _dropDownListElement_PopupClosed(object sender, RadPopupClosedEventArgs args)
    {
        if (elementUnderMouse == null)
        {
            return;
        }
        if (_dropDownListElement.SelectedIndex == -1)
            return;

        var pageSize = Convert.ToInt32(elementUnderMouse.Data.Value);
        if (pageSize == -1)
        {
            pageSize = GridControl.RowCount;
        }
        else
        {
            pageSize = pageSize <= GridControl.RowCount ? pageSize : GridControl.RowCount;
        }
        this.RowInfo.Tag = pageSize;
        GridControl.PageSize = pageSize;
        elementUnderMouse = null;
    }
    
    protected override void SetContentCore(object value)
    {
        if (_dropDownListElement != null && this.RowInfo.Tag != null)
        {
            this._dropDownListElement.SelectedValue = (int)this.RowInfo.Tag;
        }
    }

    public override bool IsCompatible(GridViewColumn data, object context)
    {
        return data is ActionColumn && context is GridTableHeaderRowElement;
    }

    protected override Type ThemeEffectiveType     
            { 
                get    
                { 
                    return typeof(GridHeaderCellElement);     
                }
            }
}

To reproduce:

GridViewTextBoxColumn textBoxColumn1 = new GridViewTextBoxColumn("Col 1");
textBoxColumn1.FieldName = "col1";
radGridView1.MasterTemplate.Columns.Add(textBoxColumn1);
GridViewTextBoxColumn textBoxColumn2 = new GridViewTextBoxColumn("Col 2");
textBoxColumn2.FieldName = "col2";
textBoxColumn2.FormatString = "{0:d}"; 
radGridView1.MasterTemplate.Columns.Add(textBoxColumn2);
radGridView1.AutoSizeColumnsMode = GridViewAutoSizeColumnsMode.Fill;

DataTable dt = new DataTable();
dt.Columns.Add("col1", typeof(string));
dt.Columns.Add("col2", typeof(DateTime));
for (int i = 0; i < 10; i++)
{
    dt.Rows.Add("Item" + i, DateTime.Now.AddDays(i)); 
}
this.radGridView1.AutoGenerateColumns = false;
this.radGridView1.DataSource = dt;

Right click the row header cell and select Copy. The  following exception occurs although we don't have a GridViewDateTimeColumn : System.InvalidCastException was unhandled
  HResult=-2147467262
  Message=Unable to cast object of type 'Telerik.WinControls.UI.GridViewTextBoxColumn' to type 'Telerik.WinControls.UI.GridViewDateTimeColumn'.
  Source=Telerik.WinControls.GridView
  StackTrace:
       at Telerik.WinControls.UI.MasterGridViewTemplate.CopyRows(String format, Boolean cut, Boolean cutOperation, StringBuilder content)
       at Telerik.WinControls.UI.MasterGridViewTemplate.ProcessContent(String format, Boolean cut, Boolean cutOperation)
       at Telerik.WinControls.UI.MasterGridViewTemplate.CopyContent(Boolean cut)
       at Telerik.WinControls.UI.MasterGridViewTemplate.Copy()
       at Telerik.WinControls.UI.GridDataRowElement.copyItem_Click(Object sender, EventArgs e)
       at Telerik.WinControls.RadElement.OnClick(EventArgs e)
       at Telerik.WinControls.UI.RadButtonItem.OnClick(EventArgs e)
       at Telerik.WinControls.UI.RadMenuItem.OnClick(EventArgs e)
       at Telerik.WinControls.RadElement.DoClick(EventArgs e)
       at Telerik.WinControls.RadElement.RaiseBubbleEvent(RadElement sender, RoutedEventArgs args)
       at Telerik.WinControls.RadItem.RaiseBubbleEvent(RadElement sender, RoutedEventArgs args)
       at Telerik.WinControls.RadElement.RaiseRoutedEvent(RadElement sender, RoutedEventArgs args)
       at Telerik.WinControls.RadElement.RaiseBubbleEvent(RadElement sender, RoutedEventArgs args)
       at Telerik.WinControls.RadItem.RaiseBubbleEvent(RadElement sender, RoutedEventArgs args)
       at Telerik.WinControls.RadElement.RaiseRoutedEvent(RadElement sender, RoutedEventArgs args)
       at Telerik.WinControls.RadElement.DoMouseUp(MouseEventArgs e)
       at Telerik.WinControls.ComponentInputBehavior.OnMouseUp(MouseEventArgs e)
       at Telerik.WinControls.RadControl.OnMouseUp(MouseEventArgs e)
       at System.Windows.Forms.Control.WmMouseUp(Message& m, MouseButtons button, Int32 clicks)
       at System.Windows.Forms.Control.WndProc(Message& m)
       at System.Windows.Forms.ScrollableControl.WndProc(Message& m)
       at Telerik.WinControls.RadControl.WndProc(Message& m)
       at Telerik.WinControls.UI.RadPopupControlBase.WndProc(Message& m)
       at System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message& m)
       at System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m)
       at System.Windows.Forms.NativeWindow.DebuggableCallback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)
       at System.Windows.Forms.UnsafeNativeMethods.DispatchMessageW(MSG& msg)
       at System.Windows.Forms.Application.ComponentManager.System.Windows.Forms.UnsafeNativeMethods.IMsoComponentManager.FPushMessageLoop(IntPtr dwComponentID, Int32 reason, Int32 pvLoopData)
       at System.Windows.Forms.Application.ThreadContext.RunMessageLoopInner(Int32 reason, ApplicationContext context)
       at System.Windows.Forms.Application.ThreadContext.RunMessageLoop(Int32 reason, ApplicationContext context)
       at System.Windows.Forms.Application.Run(Form mainForm)
       at _1075342CopyText.Program.Main() in d:\Projects\1075342CopyText_Binding\Program.cs:line 17
       at System.AppDomain._nExecuteAssembly(RuntimeAssembly assembly, String[] args)
       at System.AppDomain.ExecuteAssembly(String assemblyFile, Evidence assemblySecurity, String[] args)
       at Microsoft.VisualStudio.HostingProcess.HostProc.RunUsersAssembly()
       at System.Threading.ThreadHelper.ThreadStart_Context(Object state)
       at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
       at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
       at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
       at System.Threading.ThreadHelper.ThreadStart()
  InnerException: 

Workaround: use a GridViewDateTimeColumn 

Please refer to the attached gif file illustrating how to reproduce the error with the Demo application.

Workaround: this.radGridView1.UseScrollbarsInHierarchy = true;

To reproduce:

public RadForm1()
{
    InitializeComponent();

    DataTable dt = new DataTable();
    dt.Columns.Add("Id");
    dt.Columns.Add("Name");
    for (int i = 0; i < 50; i++)
    {
        dt.Rows.Add(i, "Data" + i);
    }

    this.radGridView1.DataSource = dt;
    this.radGridView1.AutoSizeColumnsMode = Telerik.WinControls.UI.GridViewAutoSizeColumnsMode.Fill;

    this.radGridView1.AutoSizeRows = false;
}

private void RadForm1_Load(object sender, EventArgs e)
{
    this.radGridView1.Rows[5].MinHeight = 80;
    this.radGridView1.Rows[5].MaxHeight = 100;
}

The Min/MaxHeight is not respected even when resizing the row.

Workaround: set the Height property.

To reproduce:
- Subscribe to the CellClick event 
- Click several times in the grid with the right mouse button. 
- At some point, the CellClick event will be executed. 

Workaround:
- Use the Click event:

private void RadGridView1_Click(object sender, EventArgs e)
{
    var args = e as MouseEventArgs;
    if (args.Button == MouseButtons.Left)
    {
        var clickedCell = radGridView1.ElementTree.GetElementAtPoint(args.Location) as GridDataCellElement;
        if (clickedCell != null)
        {
            //add your code here
        }
    }
}

Use attached project to reproduce. The video shows what steps you need to take. 

Workaround:
Use CellEndEdit instead. 

Use the attached project to reproduce. The video shows what steps you need to take. 

To reproduce:

private void Form2_Load(object sender, EventArgs e) 
{ 
    this.productsTableAdapter.Fill(this.nwindDataSet.Products); 
    this.categoriesTableAdapter.Fill(this.nwindDataSet.Categories);

    this.radGridView1.AutoGenerateHierarchy = true;
    this.radGridView1.DataSource = this.nwindDataSet;
    this.radGridView1.DataMember = "Categories";
    this.radGridView1.MasterTemplate.AutoSizeColumnsMode = GridViewAutoSizeColumnsMode.Fill;
    this.radGridView1.MasterTemplate.Templates.First().AutoSizeColumnsMode = GridViewAutoSizeColumnsMode.Fill;

    GridViewSummaryItem summaryItem = new GridViewSummaryItem();
    summaryItem.Name = "CategoryID";
    summaryItem.Aggregate = GridAggregateFunction.Count;
    GridViewSummaryRowItem summaryRowItem = new GridViewSummaryRowItem();
    summaryRowItem.Add(summaryItem);
    this.radGridView1.SummaryRowsTop.Add(summaryRowItem);

    GridViewSummaryItem summaryItem2 = new GridViewSummaryItem();
    summaryItem2.Name = "UnitPrice";
    summaryItem2.Aggregate = GridAggregateFunction.Sum;
    GridViewSummaryRowItem summaryRowItem2 = new GridViewSummaryRowItem();
    summaryRowItem2.Add(summaryItem2);
    this.radGridView1.MasterTemplate.Templates.First().SummaryRowsTop.Add(summaryRowItem2); 
}

private void SetNumberFormat()
{
    this.radGridView1.Columns["CategoryID"].FormatString = "{0:F4}";
    this.radGridView1.SummaryRowsTop[0][0].FormatString = "{0:F4}";

    this.radGridView1.MasterTemplate.Templates.First().Columns["UnitPrice"].FormatString = "{0:F4}";
    this.radGridView1.MasterTemplate.Templates.First().SummaryRowsTop[0][0].FormatString = "{0:F4}";
}

private void radButton1_Click(object sender, EventArgs e)
{
    SetNumberFormat();
}

Workaround: Clear and add back the summary rows when a value in the child template is changed. 
private void radButton1_Click(object sender, EventArgs e)
{
    this.radGridView1.MasterTemplate.Templates.First().SummaryRowsTop.Clear();

    GridViewSummaryItem summaryItem2 = new GridViewSummaryItem();
    summaryItem2.Name = "UnitPrice";
    summaryItem2.Aggregate = GridAggregateFunction.Sum;
    GridViewSummaryRowItem summaryRowItem2 = new GridViewSummaryRowItem();
    summaryRowItem2.Add(summaryItem2);
    this.radGridView1.MasterTemplate.Templates.First().SummaryRowsTop.Add(summaryRowItem2); 

    SetNumberFormat();
}

To reproduce:
- Add one-to-many relations hierarchy 3 or more child templates.
- Export the grid using GridViewSpreadExport
- The child rows of the last parent row are missing.

Workaround:
Add an empty parent row at the end of the grid. 

To reproduce:

Sub New()

    InitializeComponent()

    Dim dt As New DataTable()
    dt.Columns.Add("Price", GetType(System.Double))
    dt.Columns.Add("Name", GetType(System.String))
    dt.Columns.Add("Nr", GetType(System.Double))
    For i As Integer = 0 To 49
        dt.Rows.Add(i, "Data" & i, i)
    Next
    With Me.RadGridView1
        .DataSource = dt
        .Columns("Price").FormatString = "{0:C2}"
        .Columns("Nr").FormatString = "{0:N1}"
        .Columns("Price").ExcelExportType = Export.DisplayFormatType.Currency
        '
        .AutoSizeColumnsMode = Telerik.WinControls.UI.GridViewAutoSizeColumnsMode.Fill
    End With
    Me.RadGridView1.Columns("Price").ExcelExportType = Export.DisplayFormatType.Currency

    Me.RadGridView1.Columns("Nr").ExcelExportType = Export.DisplayFormatType.Custom
    Me.RadGridView1.Columns("Nr").ExcelExportFormatString = "{0:N1}"

    Me.RadGridView1.AutoSizeColumnsMode = Telerik.WinControls.UI.GridViewAutoSizeColumnsMode.Fill

End Sub

Private Sub RadButton1_Click(sender As Object, e As EventArgs) Handles RadButton1.Click
    Dim spreadStreamExport As New GridViewSpreadStreamExport(Me.RadGridView1)
    spreadStreamExport.ExportVisualSettings = True
    Dim fileName As String = "..\..\" + DateTime.Now.ToLongTimeString().Replace(":", "_").ToString() + ".xlsx"
  
    spreadStreamExport.RunExport(fileName, New SpreadStreamExportRenderer())
    Process.Start(fileName)
End Sub

Workaround:
Me.RadGridView1.Columns("Nr").ExcelExportType = Export.DisplayFormatType.Fixed

AddHandler spreadStreamExport.CellFormatting, AddressOf CellFormatting
Private Sub CellFormatting(sender As Object, e As SpreadStreamCellFormattingEventArgs)
        If e.ExportCell.ColumnIndex = 2 Then
            e.ExportCell.ExportFormat = "0.0"
        End If
    End Sub

The specified format in the DisplayFormat attribute should be considered when automatically generating the GridViewDateTimeColumn.

public RadForm1()
{
    InitializeComponent();

    List<Item> items = new List<Item>();
    for (int i = 0; i < 5; i++)
    {
        items.Add(new Item(DateTime.Now.AddDays(i)));
    }

    this.radGridView1.DataSource = items;
    this.radGridView1.AutoSizeColumnsMode = Telerik.WinControls.UI.GridViewAutoSizeColumnsMode.Fill;
}

public class Item
{
    [System.ComponentModel.DisplayName("My Date")]
    [System.ComponentModel.DataAnnotations.DisplayFormat(DataFormatString = "{0:MM/dd/yyyy}")]
    public DateTime Date { get; set; }

    public Item(DateTime date)
    {
        this.Date = date;
    }
}

To reproduce: please refer to the attached gif file and sample project. The multiple newly added rows are selected only when the grid is not sorted.

Workaround: use Begin/EndUpdate when adding multiple rows
 private void radButton1_Click(object sender, EventArgs e)
 {
     this.radGridView1.ClearSelection();
     this.radGridView1.BeginUpdate();
     for (int i = 0; i < 3; i++)
     {
         GridViewDataRowInfo row = new GridViewDataRowInfo(this.radGridView1.MasterView);
         row.IsSelected = true;
         row.IsCurrent = true;
         row.Cells["Id"].Value = this.radGridView1.Rows.Count;
         row.Cells["Name"].Value = "Row" + row.Cells["Id"].Value;
         this.radGridView1.Rows.Add(row);
     }

     this.radGridView1.EndUpdate();
 }

To reproduce:

1. Use the following code:
public Form1()
{
    InitializeComponent();

    this.radGridView1.EnableFiltering = true;

    GridViewDecimalColumn col = new GridViewDecimalColumn();
    col.Name = "Calculated Column";
    col.HeaderText = "Order value";
    radGridView1.Columns.Add(col);
    radGridView1.Columns["Calculated Column"].Expression = "Freight/Sum(Freight)";
}

private void Form1_Load(object sender, EventArgs e)
{ 
    this.ordersTableAdapter.Fill(this.nwindDataSet.Orders);

    this.radGridView1.DataSource = this.ordersBindingSource;
    this.radGridView1.AutoSizeColumnsMode = GridViewAutoSizeColumnsMode.Fill;
    
    GridViewSummaryItem summaryItem = new GridViewSummaryItem();
    summaryItem.Name = "Freight";
    summaryItem.Aggregate = GridAggregateFunction.Sum ;
    GridViewSummaryRowItem summaryRowItem = new GridViewSummaryRowItem();
    summaryRowItem.Add(summaryItem);
    this.radGridView1.SummaryRowsTop.Add(summaryRowItem);
    this.radGridView1.SummaryRowsBottom.Add(summaryRowItem);
}

2. Filter the grid by EmployeeID for example. You will notice that the summary item for Freight is recalculated considering the filtered rows. However, the calculated column doesn't update its values.

To reproduce:

Sub New()

    InitializeComponent()

    Dim dt As New DataTable
    dt.Columns.Add("Id", GetType(Integer))
    dt.Columns.Add("Name", GetType(String))

    For index = 1 To 200000
        dt.Rows.Add(index, "Item" & index)
    Next
    Me.RadGridView1.DataSource = dt

    Me.RadGridView1.MultiSelect = True
    Me.RadGridView1.SelectionMode = Telerik.WinControls.UI.GridViewSelectionMode.CellSelect
End Sub

Private Sub RadButton1_Click(sender As Object, e As EventArgs) Handles RadButton1.Click
    Dim sw As New Stopwatch
    sw.Start()

    Dim mi As MethodInfo = GetType(GridViewSelectedCellsCollection).GetMethod("BeginUpdate", BindingFlags.Instance Or BindingFlags.NonPublic)
    mi.Invoke(Me.RadGridView1.MasterTemplate.SelectedCells, Nothing)
    For Each row As GridViewDataRowInfo In Me.RadGridView1.Rows
        row.Cells("Name").IsSelected = True
    Next
    
    Dim mi2 As MethodInfo = GetType(GridViewSelectedCellsCollection).GetMethod("EndUpdate", BindingFlags.Instance Or BindingFlags.NonPublic)
    mi2.Invoke(Me.RadGridView1.MasterTemplate.SelectedCells, New Object() {True})

    sw.Stop()
    RadMessageBox.Show(sw.ElapsedMilliseconds)
End Sub

To reproduce:
- Create load on demand hierarchy.
- Open the excel filter popup.
- The RowSourceNeeded event fires for  all rows.

Workaround:
public class MyGridHeaderCellElement : GridHeaderCellElement
{
  
    public MyGridHeaderCellElement(GridViewDataColumn col, GridRowElement row) : base(col, row)
    {
    }
  
    protected override Type ThemeEffectiveType
    {
        get { return typeof(GridHeaderCellElement); }
    }
  
    protected override IGridFilterPopup CreateFilterPopup()
    {
        this.GridControl.Tag = "FileterInitializing";
        return base.CreateFilterPopup();
    }
}
// in the main forms you cab skip the event code execution while the popup is initialized
private void RadGridView1_FilterPopupInitialized(object sender, FilterPopupInitializedEventArgs e)
{
    this.radGridView1.Tag = null;
}
  
private void RadGridView1_CreateCell(object sender, GridViewCreateCellEventArgs e)
{
  
    if (object.ReferenceEquals(e.CellType, typeof(GridHeaderCellElement)))
    {
        e.CellType = typeof(MyGridHeaderCellElement);
    }
}
void radGridView1_RowSourceNeeded(object sender, GridViewRowSourceNeededEventArgs e)
{
    if (radGridView1.Tag != null && radGridView1.Tag == "FileterInitializing")
    {
        return;
    }
    //other code
}