when using the flowing setup:
<telerik:RadCartesianChart.ChartBehaviors>
<telerik:ChartSelectionBehavior x:Name="selection"
SeriesSelectionMode="None"
DataPointSelectionMode="Single"
SelectionChanged="selection_SelectionChanged"/>
</telerik:RadCartesianChart.ChartBehaviors>
the selection behavior on data point does not fire on WInUI on Cartesian series. It works for PieSeries.