progressOn is not working with splitAt method

hi. i found some problem when i used progressOn and splitAt method the same time.

usually Grid is blocked using progressOn method

however, splitAt and progressOn is going on the same time.

i checked Grid on right side of splitAt was blocked, but left side was enable area.

is this normal situation?

attach my screen shot. please anybody answer me~~

splitAt call reconstructs the grid which may cause some side effects
if progressOn was used after splitAt - there must be no any side effects

Can you share a full code, where issue can be checked ?