To reproduce:

Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load 
    Me.CustomersTableAdapter.Fill(Me.NwindDataSet.Customers) 
    Dim view As New ColumnGroupsViewDefinition()
    view.ColumnGroups.Add(New GridViewColumnGroup("Customer Contact"))
    view.ColumnGroups.Add(New GridViewColumnGroup("Details"))
    view.ColumnGroups(1).Groups.Add(New GridViewColumnGroup("Address"))
    view.ColumnGroups(1).Groups.Add(New GridViewColumnGroup("Contact"))
    view.ColumnGroups(0).Rows.Add(New GridViewColumnGroupRow())
    view.ColumnGroups(0).Rows(0).Columns.Add(Me.RadGridView1.Columns("CompanyName"))
    view.ColumnGroups(0).Rows(0).Columns.Add(Me.RadGridView1.Columns("ContactName"))
    view.ColumnGroups(0).Rows(0).Columns.Add(Me.RadGridView1.Columns("ContactTitle"))

    view.ColumnGroups(1).Groups(0).Rows.Add(New GridViewColumnGroupRow())
    view.ColumnGroups(1).Groups(0).Rows(0).Columns.Add(Me.RadGridView1.Columns("Address"))
    view.ColumnGroups(1).Groups(0).Rows(0).Columns.Add(Me.RadGridView1.Columns("City"))
    view.ColumnGroups(1).Groups(0).Rows(0).Columns(1).RowSpan = 40
    view.ColumnGroups(1).Groups(0).Rows(0).Columns.Add(Me.RadGridView1.Columns("Country"))

    view.ColumnGroups(1).Groups(1).Rows.Add(New GridViewColumnGroupRow())
    view.ColumnGroups(1).Groups(1).Rows(0).Columns.Add(Me.RadGridView1.Columns("Phone"))
    view.ColumnGroups(1).Groups(1).Rows(0).Columns.Add(Me.RadGridView1.Columns("Fax"))

    RadGridView1.ViewDefinition = view
    Dim summaryItem As New GridViewSummaryItem()
    summaryItem.Name = "Address"
    summaryItem.Aggregate = GridAggregateFunction.Count
    Dim summaryRowItem As New GridViewSummaryRowItem()

    summaryRowItem.Add(summaryItem)
    Me.RadGridView1.SummaryRowsTop.Add(summaryRowItem)
    Me.RadGridView1.MasterView.SummaryRows(0).PinPosition = PinnedRowPosition.Top
    Me.RadGridView1.MasterView.SummaryRows(0).Height = 20
End Sub


Workaround: use the ViewCellFormatting event and set the TextAlignment property to MiddleTop for the summary cells.