Ranger - "Higher Vampire" [5th Campaign, 5th Mission]

I had a glitch at the beginning (I bought the game). I gathered an army and defeated Nicholas, and then he appeared in front of all my castles and attacked them three times each! I barely managed to hold out, and then he disappeared somewhere. I caught up with him, and he already had a super army! Has anyone else experienced this? Later, it seemed to be fine!

Added after 16 hours and 59 minutes
Maybe someone can give me some advice! When I finally killed him, there was a video showing him still alive with his army, and Faydeen was reciting poetry!