Cannot Create or Join Draft Pick Lobby [6.12 | 26.06.16]

Suddenly today, I cannot create or join a draft pick lobby (normal or ranked). I click "Launch" after selecting the map and gamemode, and after that the launcher says "Please Wait", doesn't load, and after ~30 seconds jumps back to the home screen. This happens when I get invited to a draft pick lobby as well.

I've tried restarting the client and my computer, repairing, reinstalling the game. Nothing works. I've already contacted the support, nothing works.