Huuuuuge bug that randomly locks the game into the background and won't respond to actions

At very very random times, the game will just lock me out of anything. It'll become absolutely unresponsive. No clicks. No key presses. Nothing. Tabbing in and out doesn't work. Even closing down the game and restarting it doesn't help. It's incredibly weird and very frustrating, because of how random it is.

I can play 10 games in a row and not have a single problem, yet one single moment and the game just will not respond to my actions. It's like it's permanently in the background and nothing I do will bring it into the foreground. Minimizing it and restoring it didn't work. Restarting the game didn't work. Nothing seemed to work at all.

Has anyone else experienced this issue?