Actipro ThemedDataGrid throws exception after scrolling to new row line

Hi,

I keep getting this exception after scrolling to new row line in gridview:

at System.Windows.Controls.ItemContainerGenerator.System.Windows.Controls.Primitives.IItemContainerGenerator.StartAt(GeneratorPosition position, GeneratorDirection direction, Boolean allowStartAtRealizedItem)
at System.Windows.Controls.VirtualizingStackPanel.MeasureOverrideImpl(Size constraint, Nullable'1& lastPageSafeOffset, List'1& previouslyMeasuredOffsets, Boolean remeasure)
at System.Windows.Controls.VirtualizingStackPanel.MeasureOverride(Size constraint)
at System.Windows.Controls.Primitives.DataGridRowsPresenter.MeasureOverride(Size constraint)
at System.Windows.FrameworkElement.MeasureCore(Size availableSize)

....

at System.Windows.Interop.ComponentDispatcherThread.RaiseThreadMessage(MSG& msg)
at System.Windows.Threading.Dispatcher.TranslateAndDispatchMessage(MSG& msg)
at System.Windows.Threading.Dispatcher.PushFrameImpl(DispatcherFrame frame)
at System.Windows.Application.RunDispatcher(Object ignore)
at System.Windows.Application.RunInternal(Window window)

at DNVS.Nauticus.Hull.App.Main()

The scenario is as follows:

- create a WPF grid having NewRowTemplateBehavior.Template set up and a fixed height.

- fill in the grid with number of items exceeding one page

- scroll the grid the way that new item placeholder row disappears from the grid but pressing "PageUP/Down" would make it visible.

- press "PageDown" and see that the exception is raised

This issue happens only when I set NewRowTemplateBehavior.Template to non-empty value (ie. <TextBlock>New row</TextBlock>) 

Version of DataGrid.Contrib.Wpf I'm using is 14.1.600.0. The issue can be replicated also within ActiPro WPF demos for version 14.1.600.0.

I'm hoping for some help from your side how to workaround this problem.

Many thanks,

AD