Before I raise an official ticket (though that seems to be the only way to get a response from OT) ...
I have on occasion had issues where a folder does not close, and the folder does not reopen, on occasion. No error or other message is logged, it just "spins" or goes white and never finishes closing. It doesn't seem to matter if a form has activity to perform upon "when action completed" or "when user exists form" or not. It just spins. I've had this happen in a few different solutions and actions -- it is not repeatable nor consistent. It seems rather random.
Unfortunately, a primary user experienced this yesterday testing our primary V9 rewrite solution ... to the point that they now have a bad opinion of V9.