Since the last patch I've had several arena games where the timer will count down to zero during my opponent's turn and the turn never ends. I've tried waiting but nothing changes. When I refresh the page I go back to main screen and it ends up being a loss.
I also had a few games yesterday that froze during arena, all versus the same player. Haven't had it happen since so I'm not sure if that bug has been fixed or not, but figured I'd mention it as well.