I'm running into a problem in the final fight in the Drombach region. It's a special fight, so you have to fill an event bar and won't win it by simply killing every enemy unit on the field. Either way, the game freezes after the first round, only showing "allied reinforcements arriving". I've tried reducing the amount of troops by leaving people behind at the trading post, but I can only leave three people behind in the local one, which didn't help since the game always forces one unit to be left undeployed as reinforcement even if there are still deployment spots left on the field. Tried reloading, and both killing every enemy unit on the field and leaving some alive. Since I've leveled up most of my troop pretty far and it was quite a pain to capture all those animals (I won't fight a 40+ group of white bears again, thank you), I'm opposed to just letting them be killed off to avoid a game breaking bug, and would rather not take a full round trip to every trading post to drop off three guys at each one in the hope that this pushes me below the reinforcement limit. However, this renders the fight impossible to win, so any help would be appreciated.

Using GOG Galaxy, so I suppose my game is up to date as far as possible.