I've hit a bug kinda like the one Kaiyurin mentions a few posts back...
All of the sudden thing (idols, songs, events...) will become undraggable. (Or undroppable, since I can grab them and move them. The items in the doctor's window light up.) It requires a save-and-quit to reset. Things will be normal for a minute or two, and then it happens again.
Update: Yeah, this should be called the draggable-but-not-droppable bug. I can grab something, and the cursor icon changes, but when I hover over a drop location and drop nothing happens.
This happens on all items on the main (building/staff) screen. It does not happen on the (single) formation screen.
Bug still present in Beta 5.1. It took about an hour or so of game play to appear, and then steadily becomes more frequent as play time increases.
Saving and reloading clears the problem.
Interesting... I was about to post that I started a new save and encountered the same pattern - no problem at first, then it popped up after I'd played for a while. But I had added a doctor on the floor above the "rent free" floor before encountering it - just as BrassCrassus posted just a few minutes ago.