I think it's connected to the POI reset stability issue.
Yeah, it does seem that the stability problems are related to the POI being reset for a quest. I've seen this in at least 3 different POI since 3.0. Hopefully they figure it out soon. This isn't quite as widespread (I think) than what was happening in the 2.x versions with quest resets, but it's still a problem. I've had more issues with this game in 3.x than probably any time before that. Not that there are a LOT of problems now, but I've crashed at least twice to desktop with the Unity crash handler popping up and that never happens.Now I'm playing on a brand new world with missions and trading turned off. Not seeing anything missing or mysteriously collapsed.