I've had something similar happen where my vampire colonist revert to human. I traced the debug log and got this:

request : ROMV_LegendaryVampires, ROMV_FirstVampireKind
UnityEngine.StackTraceUtility:ExtractStackTrace ()
Verse.Log:Message (string)
raceQuestPawn.patch_PawnGenerator_GeneratePawn:Prefix (Verse.PawnGenerationRequest&)
(wrapper dynamic-method) Verse.PawnGenerator:Verse.PawnGenerator.GeneratePawn_Patch8 (Verse.PawnGenerationRequest)
Vampire.VampireGen:GenerateVampire (int,Vampire.BloodlineDef,Verse.Pawn,RimWorld.Faction,bool)
Vampire.WorldComponent_VampireTracker:get_FirstVampire ()
Vampire.HediffVampirism:PostTick ()
(wrapper dynamic-method) Verse.Pawn_HealthTracker:Verse.Pawn_HealthTracker.HealthTick_Patch5 (Verse.Pawn_HealthTracker)
(wrapper dynamic-method) Verse.Pawn:Verse.Pawn.Tick_Patch3 (Verse.Pawn)
Verse.TickList:Tick ()
(wrapper dynamic-method) Verse.TickManager:Verse.TickManager.DoSingleTick_Patch7 (Verse.TickManager)
Verse.TickManager:TickManagerUpdate ()
(wrapper dynamic-method) Verse.Game:Verse.Game.UpdatePlay_Patch2 (Verse.Game)
(wrapper dynamic-method) Verse.Root_Play:Verse.Root_Play.Update_Patch1 (Verse.Root_Play)


Anyone make heads or tails of this?

It's happened to me on 3 separate occasions, and 2 consecutive occasions

This seems like a similar situation I encountered, but with severe consequences for the pawn.

I sent my one pawn with vampirism out on a caravan. During the caravan travel, I saved the game and quit Rimworld. When I started the game up again and continued playing, I noticed that the caravan icons (rest, abandon, etc..) on the world map were missing. When the caravan arrived and began loading the local map, it looks like all health effects are removed from the pawn. No disciplines show. Once the local map fully loads and the pawn starts moving towards the settlement, they drop dead from starvation.

The only mods I'm using are this one, including dependencies, and MendAndRecycle

I'm fairly certain it has to do with the Biotech DLC. It worked fine before I bought BT

Originally posted by whiteglove:

I'm fairly certain it has to do with the Biotech DLC. It worked fine before I bought BT

So at the time I did not own the Biotech DLC, so it stands for reason that I did not have the DLC installed overall, so this is unlikely. I do possess the Biotech DLC today, but I have not touched this save in a year now.