Screen does not minimize/Game does not load

I make a video of the problems that are happening to me recently with Mac.

At the beginning of the video I show how the game can not be minimized (0:00 - 0:08), this happens since I switched to High Sierra (October - November last year).

Then I show how the game runs quite well in general but when I start a game starts to fail, mainly does not load the game, this happens to me with any game mode (PvP). This problem started from Saturday after update the game.

Please riot help me with this, I just can't play!

forget to comment that reinstall the game on 2 occasions and try to repair it on 4 occasions