Okay, not sure if this was mentioned in this thread, but I just played a game where on turn 100 I stormed the final castle of Pangea and I figured it would be an easy victory. When the turn summary Messages came up, I saw that my entire wiped out but SO DID THEIRS. Every single unit in the battle was slaughtered!
So I go to watch the replay of the battle and in about 4 turns my army enters the courtyard and routes the enemy. Easy victory, as I thought it would, with me only taking about 1% casualties. What then happened is where the bug is. My army was just standing still, doing nothing while the castle was shooting arrows at them. There was no enemy left alive, and my guys were alone on the battlefield standing motionless with the castle just shooting arrows at them until they all died after what was probably several hundred turns (the arrows really didn't do much damage, and I had units like Iron Dragons).
I pressed "w" to see if there was a unit stuck in the castle or something, and I saw one of the enemy's units with negative Hit Points still standing there next to a wall (I forget what unit, but I'm pretty sure it was just a regular unit, not a hero or anything). Obviously, the unit should have been killed and erased from the battle, but it was bugged and stuck there and none of my units could attack it so they all stood around and let the castle kill them
Very frustrating since it was ALL of my forces and it took me many turns to rebuild that army to conquer it again, this time without the bug.