Screen blacks out after champ select after patch 6.2

[patch 6.2] After champ select, the screen blacks out. Doesn't matter which game mode: normal, ranked, custom...can't even spectate (i made sure there was no Sona in the game). I don't run LOLReplay and I'm clearly not the only one having this issue. I'm having a MAC.

I didn't plan to report this bug as a lot of users clearly have reported the same problem, but no action was taken. So I just try to get the word out.