Sometimes the enemy palace just "vanishes". I was taking down the temples/guilds of my last enemy before I stormed their palace when all the sudden it vanished before my eyes and said "you've won!" I noticed it did this with another enemy palace, too, but wasn't sure if I missed it being destroyed since I did have a bounty on it. I just was like "hmm...I guess that was destroyed faster than I thought". But there was no "evidence" of it being destroyed. The wreckage usually stays there for a bit of time. I'm still going to take the win...they were as good as dead anyway.

Three problems i've encountered on this mission is:
1. Had a situation where my Fallen Angel and Necro minions were pursuing a bounty on my own building, i suppose the Angels may go Rogue but minions though?
2. The game randomly crashes for me around Day 23, never happened until this mission. Not sure why but perhaps some problem having multiple Kingdoms using the Sorcerer's spells such as gate?
3. Sometime when i'm loading a saved game on this quest, i see all the enemy buildings on the map, which kind of gives me an unfair advantage here. Not sure if there's an workaround.

Playing on Win10.