If I understand your scenario correctly you report that if the data is being generated at runtime and it is being selected by the ChartDataSource, your chart is updating. If this is your scenario I would like to say that this is the expected behavior of the RadCartesianChart. It is expected that when the ItemsSource of the chart is undated its visualization is also updated. If you need to update the chart only one time you need to ensure that your data for the "current" aggregation is created and ready to use before updating the ChartDataSource.
If however, this is not your scenario please provide us with more detailed information, clarifying your exact scenario and requirements.
Pavel R. Pavlov
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