Im on PC, playing a sealed event.
When select attack, the game "hiccups" for a second, and becomes stuck on the select attackers step, after the attacker is moved "forward" but just before it is tapped, and the game "freezes" in an odd way. Anymations still play, I could still send and receive emotes. The timer started counting down, but even after running out nothing happened.

I had to quit arena after nearly ten minutes of waiting for something to happen. Except now I can't connect to the server, logging in gives me two odd log in errors in succession: lost connection to the server (I click "reconnect") and authentication failed for Niedude (my account name).

I had two losses. I believe this has cost me my chance to break even on my 2000 gems investment (I was 1 victory away from it).