I found this thread after running into something similar in 10.2.100.36. We’re planning to upgrade soon, so I’ll see if the problem still exists in the newer version.
I followed the instructions in this thread to put a combo box in a grid. The combo box already existed elsewhere in the form. Both combos initially look correct, and both save the correct values when changed and saved. But when the combo in the grid is changed, the original sometimes goes blank. Sometimes it refreshes if you switch tabs a few times, sometimes not.