Not a bug, undead will never regenerate mana or stamina.
Your bug, in this case, is adeptus mechanus which is trying to change the backstories of undead which don't have any backstory at all (referencing a null value).

wait lemme be clearer, the pawns that are not regenerating mana or stamina are not undead they have been with me since the start of the game and i have watched them regen mana/stamina many times. One of them happens to be a death knight and while his stamina would not regenerate his hate would. (ring of malice). The pawns in the log are undead created by a lich and are not magically gifted. however i also have a non-undead level pawn with magic who has 0 mana upkeep and even he was not regenerating during a mana surge. Any clue whats going on and is mechanus going to be a issue? regardless thanks for the reply and thanks for making such a cool mod.

Some people have reported issue with stamina or mana regenerating after doing some quests from the witcher mod. Others seem to have issues with the pawn morpher, both look like they are modifying/removing some of the components necessary for mages/fighters. I'll be looking at both of those mods to see if there's some way to make them compatible, but those are the issues im aware of at this time.

I'm running into the same issue with mana/stamina regeneration and I am not using either of those mods. https://gist.github.com/ea6a0db3dbe076ae2fd4f193e77c8ca3
I tried entering dev mode and created a mana surge but it doesn't fix.

This seems to still be happening, as none of my pawns with classes are regenerating mana/stamina. Stamina/Mana Gain read 0 on everyone everywhere, and cranking the multiplier up in the settings does nothing, expectedly.

Here's the log: https://gist.github.com/3586b5d1a615f720f23c4073a350aabe

So I get a mana drain to zero on almost all my pawns whenever I enter a new area during an encounter and generate map. I've been able to repeat it via a saved game. Is there a command to set pawns mana values? Right now I'm stuck because I can't win the encounter if their mana gets drained after entering the area. I tried to increase the regen rate to 10x but it doesn't work.

Ok...so I tried again and what actually drains the mana is an event trigger for a quest! I tried loading the save game again and it shows 0 mana. However, if I restart RimWorld, the mana bar shows back up and their mana is full. Hope that helps narrow it down.

crickets....

Anyone happen found a solution for this, yet?

Originally posted by heretic:

Anyone happen found a solution for this, yet?

lol sorry to nerco this but tbh i stopped running this mod due to balance and conflict issues, i highly recommend VE psycasts as that expands on a system already in place, instead of adding a new semi-parallel one into the game, and does so far more naturally, and cleanly (UI, lore, and conflict wise)

Originally posted by CheekiBreeki:

Originally posted by heretic:

Anyone happen found a solution for this, yet?

lol sorry to nerco this but tbh i stopped running this mod due to balance and conflict issues, i highly recommend VE psycasts as that expands on a system already in place, instead of adding a new semi-parallel one into the game, and does so far more naturally, and cleanly (UI, lore, and conflict wise)

I think I might as well. I did find the classes far more interesting and fun than any of the psy stuff, imo.