<table class="table">
    <tr>
        <td class="table-active" style="width: 40px; text-align: center"><input type="checkbox" /> </td>
        <td>test</td>
    </tr>
</table>

Unable to cast object of type 'Telerik.DataSource.CompositeFilterDescriptor' to type 'Telerik.DataSource.FilterDescriptor'.
System.InvalidCastException: Unable to cast object of type 'Telerik.DataSource.CompositeFilterDescriptor' to type 'Telerik.DataSource.FilterDescriptor'.
at Telerik.Blazor.Components.Common.TableGridBase`2.LoadSearchFilter(IFilterDescriptor descriptor)
at Telerik.Blazor.Components.TelerikGrid`1.SetStateInternalAsync(GridState`1 state)
at Telerik.Blazor.Components.TelerikGrid`1.InvokeOnStateInit()
at Telerik.Blazor.Components.TelerikGrid`1.OnParametersSetAsync()
at Microsoft.AspNetCore.Components.ComponentBase.CallStateHasChangedOnAsyncCompletion(Task task)
at Microsoft.AspNetCore.Components.ComponentBase.RunInitAndSetParametersAsync()
at Microsoft.AspNetCore.Components.RenderTree.Renderer.GetErrorHandledTask(Task taskToHandle, ComponentState owningComponentState)
fail: Microsoft.AspNetCore.Components.Server.Circuits.CircuitHost[111]
Unhandled exception in circuit 'MYsaCsOgfpbyHeO0xNFpA7ViPHNUC6rpc1K9eIwVR5Y'.
System.InvalidCastException: Unable to cast object of type 'Telerik.DataSource.CompositeFilterDescriptor' to type 'Telerik.DataSource.FilterDescriptor'.
at Telerik.Blazor.Components.Common.TableGridBase`2.LoadSearchFilter(IFilterDescriptor descriptor)
at Telerik.Blazor.Components.TelerikGrid`1.SetStateInternalAsync(GridState`1 state)
at Telerik.Blazor.Components.TelerikGrid`1.InvokeOnStateInit()
at Telerik.Blazor.Components.TelerikGrid`1.OnParametersSetAsync()
at Microsoft.AspNetCore.Components.ComponentBase.CallStateHasChangedOnAsyncCompletion(Task task)
at Microsoft.AspNetCore.Components.ComponentBase.RunInitAndSetParametersAsync()
at Microsoft.AspNetCore.Components.RenderTree.Renderer.GetErrorHandledTask(Task taskToHandle, ComponentState owningComponentState)

 private async Task OnBeforeExcelExport(GridBeforeExcelExportEventArgs args)
 {
     await Task.CompletedTask;

     // Loop through all columns and fix the footer aggregate values
     // Replace the default "Sum: 1234.56" text with just the decimal number
     foreach (var column in args.Columns)
     {
         if (column.HasAggregate)
         {
             // Set the number format for the column so Excel treats it as a number
             column.Aggregate.Field.Value == "MyNewValue";
         }
     }
 }

@using System.ComponentModel.DataAnnotations

<TelerikGrid @ref="@GridRef"
             Data="@GridData"
             EditMode="@GridEditMode.Incell"
             OnUpdate="@OnGridUpdate"
             OnCreate="@OnGridCreate">
    <GridToolBarTemplate>
        <GridCommandButton Command="Add">Add Item</GridCommandButton>
    </GridToolBarTemplate>
    <GridColumns>
        <GridColumn Field="@nameof(Product.Name)" />
        <GridColumn Field="@nameof(Product.StartDate)" Title="BUG" DisplayFormat="{0:d}" />
        <GridColumn Field="@nameof(Product.EndDate)" Title="WORKAROUND" DisplayFormat="{0:d}">
            <EditorTemplate>
                @{ var editItem = (Product)context; }
                <TelerikDatePicker Value="editItem.EndDate"
                                   ValueChanged="@((DateTime? newValue) => OnGridDatePickerValueChanged(newValue, editItem))"
                                   ValueExpression="@( () => editItem.EndDate )"
                                   OnClose="@(async () => await OnGridDatePickerClose(editItem))" />
            </EditorTemplate>
        </GridColumn>
    </GridColumns>
</TelerikGrid>

@code {
    #nullable enable

    private TelerikGrid<Product>? GridRef;
    private List<Product> GridData { get; set; } = new();

    private int LastId { get; set; }

    private DateTime LastDatePickerValueChanged { get; set; } = DateTime.Now;

    private void OnGridDatePickerValueChanged(DateTime? newValue, Product editItem)
    {
        editItem.EndDate = newValue;
        LastDatePickerValueChanged = DateTime.Now;
    }

    private async Task OnGridDatePickerClose(Product editItem)
    {
        if (DateTime.Now - LastDatePickerValueChanged > TimeSpan.FromMilliseconds(500))
        {
            GridState<Product> gridState = GridRef!.GetState();

            if (gridState.EditItem is not null && gridState.EditItem.Id == editItem.Id)
            {
                // Uncomment to perform an item update instead of cancel
                // OnGridUpdate(new GridCommandEventArgs { Item = editItem });

                gridState.OriginalEditItem = null!;
                gridState.EditItem = null!;

                await GridRef.SetStateAsync(gridState);
            }
        }
    }

    private void OnGridCreate(GridCommandEventArgs args)
    {
        var createdItem = (Product)args.Item;

        createdItem.Id = ++LastId;

        GridData.Insert(0, createdItem);
    }

    private void OnGridUpdate(GridCommandEventArgs args)
    {
        var updatedItem = (Product)args.Item;
        var originalItemIndex = GridData.FindIndex(i => i.Id == updatedItem.Id);

        if (originalItemIndex != -1)
        {
            GridData[originalItemIndex] = updatedItem;
        }
    }

    protected override void OnInitialized()
    {
        for (int i = 1; i <= 5; i++)
        {
            GridData.Add(new Product()
            {
                Id = ++LastId,
                Name = $"Product {LastId}",
                Price = Random.Shared.Next(0, 100) * 1.23m,
                Quantity = Random.Shared.Next(0, 1000),
                StartDate = DateTime.Today.AddDays(-Random.Shared.Next(60, 1000)),
                EndDate = DateTime.Today.AddDays(Random.Shared.Next(1, 60)),
                IsActive = LastId % 4 > 0
            });
        }
    }

    public class Product
    {
        public int Id { get; set; }
        [Required]
        public string Name { get; set; } = string.Empty;
        public decimal Price { get; set; }
        public int Quantity { get; set; }
        public DateTime? StartDate { get; set; }
        public DateTime? EndDate { get; set; }
        public bool IsActive { get; set; }
    }
}

<TelerikGrid Data="@GridData"
             AdaptiveMode="@AdaptiveMode.Auto"
             FilterMode="GridFilterMode.FilterMenu"
             ShowColumnMenu="true">
    <GridColumns>
        <GridColumn Field="@nameof(Product.Name)" />
        <GridColumn Field="@nameof(Product.Group)" />
        <GridColumn Field="@nameof(Product.Price)" DisplayFormat="{0:c2}" />
        <GridColumn Field="@nameof(Product.Quantity)" DisplayFormat="{0:n0}" />
        <GridColumn Field="@nameof(Product.Released)" DisplayFormat="{0:d}" />
        <GridColumn Field="@nameof(Product.Discontinued)" />
    </GridColumns>
</TelerikGrid>

@code {
    private List<Product> GridData { get; set; } = new();

    protected override void OnInitialized()
    {
        var rnd = Random.Shared;

        for (int i = 1; i <= 3; i++)
        {
            GridData.Add(new Product()
            {
                Id = i,
                Name = $"Name {i} {(char)rnd.Next(65, 91)}{(char)rnd.Next(65, 91)}",
                Group = $"Group {i % 3 + 1}",
                Price = rnd.Next(1, 100) * 1.23m,
                Quantity = rnd.Next(0, 10000),
                Released = DateTime.Today.AddDays(-rnd.Next(60, 1000)),
                Discontinued = i % 4 == 0
            });
        }
    }

    public class Product
    {
        public int Id { get; set; }
        public string Name { get; set; } = string.Empty;
        public string Group { get; set; } = string.Empty;
        public decimal Price { get; set; }
        public int Quantity { get; set; }
        public DateTime Released { get; set; }
        public bool Discontinued { get; set; }
    }
}

The TelerikGrid never loads any data. the app just hangs. 

I copied the Telerik sample from the online demo. 

 The HTML table loads perfectly.

 Using VS 2019  16.1.0 Preview 2.0.

Acquired Telerik nuget package directly from Telerik feed.

    <TelerikGrid Data=@ViewModel.GetCorePharmacies() Height="300">
        <TelerikGridColumns>
            <TelerikGridColumn Field="ID" Title="NCPDP#" />
            <TelerikGridColumn Field="NPINumber" Title="NPI#" />
            <TelerikGridColumn Field="DBAName" Title="Pharmacy" />
            <TelerikGridColumn Field="StoreNumber" Title="Store#" />
        </TelerikGridColumns>
    </TelerikGrid>

    @*<table class="table">
        <thead>
            <tr>
                <th>NCPDP</th>
                <th>NPI</th>
                <th>DBA Name</th>
                <th>Store#</th>
            </tr>
        </thead>
        <tbody>
            @foreach (var pharmacy in ViewModel.GetCorePharmacies())
            {
                <tr>
                    <td>@pharmacy.ID.ToString()</td>
                    <td>@pharmacy.NPINumber.ToString()</td>
                    <td>@pharmacy.DBAName</td>
                    <td>@pharmacy.StoreNumber</td>
                </tr>
            }
        </tbody>
    </table>*@

Any thoughts. 

<button @onclick="@MyClick">Add item</button>

void MyClick()
{
    MyData.Add(new SampleData() { ID = 46, Name = "from click" });
    StateHasChanged();
}