*[I am duplicating this response as I believe it covers the issue in your relevant bug report]
In order to make sure the latest internal build contains the proper fixes , I have prepared a small test project.
Please find it attached. It has a few buttons to add / clear column groups runtime.
In case your problem persists with this LIB , please let me know how to modify the test app in order to expose the issue. If I am able to reproduce the issue locally I will personally take care for the proper fix to be added for the very next LIB ( the next Tuesday ).
the Telerik team
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