Hello Christian,
Thank you for the project and the description.
I can confirm that this is a regression issue related to another fix including the UseLayoutRounding setting. I have updated the status of this report and also your Telerik points.
At the moment, you can work this around by avoid setting the UseLayoutRounding property to True or by setting the EnableStickyGroupHeaders to False.
Regards,
Martin Ivanov
Progress Telerik
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