I've had this same problem 3 years in a row with the online version. Apparently, the screen view is different in the desktop version because your fix isn't obvious in the online version. I tried repeatedly doing nothing different each time and it finally worked. I can't figure out why it gets hung up. It's a bug in the system which they haven't got around to fixing. One would think that they would monitor issues in this forum and deal with them in due course.
