I don't know if this can help you but when I posted my own problem in the Winforms section, here's the answer I got in the end. I did not try temporary solution because I've been busy on other things that the related project these last weeks :
Reply from Telerik starts here:
(...) It seems that you have bind the RadGridView to IQueryable
object. I added it to our public issue tracking system. It will be
addressed in one of the next releases.
In the meantime, you can handle
the update issue by simply changing the current row in that way: