I have encountered this problem multiple times, even in version 3.06. As far as I understand, it wasn't listed among the fixed bugs. I was sure that the developer had already been informed about this issue, but now I'm not so certain. I had to stop the game three times in the WT version after attempting to capture a Necropolis. In a game with Javdet, the terrain changed for him during the battle (not in the sense of the territory where the Necropolis was located), and I received a critical error message twice, after which the game closed. I've attached a screenshot.