Xoti's companion quest Lantern of Gaun is currently bugged in my playthrough. The quest progressed as normal (as I've later checked on wikis and such) and the soul extraction procedure completed successfully, with Xoti being cheerful and "sleeping like a baby" since then.
- The quest is still in my questbook, on the stage after the worsening nightmares
- It continued to update with new adra pillars found
- Xoti continued to grab the souls past the procedure
- If manually spoken to, the "how are you feeling" dialogue with Xoti is always shown as new, yet no new responses are in that tree if I pursue it
As such, Xoti seems to behave as if the quest ended with the "light" ending, but I'm not sure if this unfinished state in the quest log will result in some bizarre flag that makes the quest incomplete for possible sequel export. UPDATE: Epilogues and final talks still worked as if the quest was resolved with the light path. The quest remained as incomplete in the log.
The quest was completed on 4.0 version of the game (while I'm still playing that same playthrough on the newest Steam build). Link to the savegame: http://klardendum.com/poe/poe2save.zip
As a bonus, two Bounty quests on that same file cannot be completed:
Huana's bounty missions cannot be turned in since the start of Act 3 since Barati is simply missing from the game world.
RDC bounty missions cannot be turned in (but with the quest not marked as failed) due to me siding with Huana and making the entire district there hostile to me after the quest was complete.