Can't Click on Anything in Game?

This happens quite a bit as of late. I load into a game and can't click to buy, to level skills or even adjust the camera. It happens from time to time and I can occasionally fix it by tabbing out of the match and tabbing back in.

Now, that doesn't fix the issue. I typically have to frantically click on leave match and hope it will process it. This bug has been going on for a year and is more apparent now. I play LoL mostly on a MAC but experience the same issues on a PC as well. Can someone explain what the bug is or what I can do to fix it?