Ranger "Refugees" - [5th campaign, 1st mission]

The bug might occur if you don't return the defeated garrison. If that doesn't help, you can also use a cheat code for victory (in my opinion, there's nothing unfair about it in case of a bug).

I tried returning them, but it didn't help. I also thought about using a cheat code, but I decided to replay the map. In fact, this time the development went even better. I maxed out Dark Magic, learned Blind and Dominate for the mages, and achieved a defense of 10 without any artifacts. I also have expert Logistics. Overall, everything is good. Just now, a single garrison attacked, and I successfully repelled them. I hope Biara shows up this time as she should. If not, then I'll have to use a cheat code.