Game mode: Singleplayer
Walking a few feet away from an area or simply turning around to face away from an area will cause it to completely refresh. I have had several NPC settlements that refresh just from walking a few feet away from them (most notable: Trapper’s Cabin). I have also had issues where unconscious enemies and dead bodies will completely disappear just from turning around and not facing them (occurs mostly with named thralls, oddly enough). Enemy NPCs will also just randomly disappear while in pursuit while human NPCs will even randomly disappear during battle.
Steps on how to reproduce issue: