UI sometimes stops working.

This happens in many places; the buttons simply don't work.

I'm not sure when it happens and I can't reproduce the bug, but I first encountered it when I was moving between locations and decided to level up a gem a few moments before changing locations. After that, and until I restarted the game, the button didn't work.

Friends said something similar happened with Atlas, Blight (towers), and some other buttons. But I can't guarantee it's the same bug.