I'm sure you're probably seen this in world chat by now, but anyway... The league game I was in got stuck when my opponent charged up the cannon, the manditory action wasn't getting played, neither player's clock was running. Also, the game failed to resume the battle after reloading the page. It prompts to resume, but it takes over 2 minutes to rejoin, and never succeeds. If I aborted rejoining the game, it counted as a loss for me.
There's a bug where passing when you have a mandatory action in hand stalls the game. I'm working on fixing it right now. If you lost a league game due to this, email support@cardhunter.com and we'll refund your entry fee. Sorry.