When displaying a large number of lines (e.g., 10 000) in a DataGrid it's not possible to scroll to the last line using the scroll wheel, scrolling stops at the penultimate line and the last line is not visible. Dragging the scroll bar with the pointer or using arrow keys works correctly, the issue only occurs when using the scroll wheel. Other prerequisite is that display scaling is enabled. Tested in Windows 10/11 with display scale of 125% and 150%.
Example:
App.axaml
<Application.Styles>
<actipro:ModernTheme Includes="NativeDataGrid">
<actipro:ModernTheme.Definition>
<generation:ThemeDefinition
BaseFontSize="12"
UserInterfaceDensity="Compact" />
</actipro:ModernTheme.Definition>
</actipro:ModernTheme>
</Application.Styles>
MainWindow.axaml
<DataGrid Name="TestDataGrid" AutoGenerateColumns="True" />
MainWindow.axaml.cs
TestDataGrid.ItemsSource = Enumerable.Range(1, 10000);
Drag the scroll bar near the end and scroll the rest of the way using the scroll wheel and it won't be possible to scroll to the line 10 000. Line 9 999 will be the last visible line.