[Bug][0.51] Iron golem champion doesn't attack?

Last game Verga attacked one of my cities with Mausolos(sp?), another champions, and a couple militia. It was actually pretty much undefended at the time, I didn't think he would attack, so the fight was very close. I noticed the golem wasn't doing anything except skipping it's turn every turn, and not even getting a defending bonus for it, so I save him for last. Finally it came down to just a single group of militia archers and Mausolos still at full health (100+), even when he was the last enemy alive he didn't attack, he just stood there while my archer plinked away at him doing 0-3 damage every turn. I put it on 5x speed and auto-play and watched like 100+ turns go by as my archer slowly dropped his health. Once he got to 50% health or so he moved like 2 tiles to one side, but that was the only action he took as my archer eventually killed him and won the battle.