I found a work around (toggling non-lethal attacks, which leaves enemies with 1 HP but you win fights) for a problem, but the second Hag type monster in the game can't be to made puke with the potion brewed with the latest version today 4.1.1.370 (released 6 days ago).

When one tries to throw the potion or do anything in the battle, it just says "can't use right now" which is bizarre.

At least there's a way to pass the quest with the non-lethal attack toggle, hope this helps anyone having issues.

You might want to spoiler that. Not everyone knows about that. Your fallback approach was my first approach... it wasn't until after losing that fight multiple times that I found the other way to do it.

Also, I can't imagine trying to do that fight without AOE or environmental damage, which will still kill someone even if you've got knockout toggled. That's gotta suck.

Both times i fought the hag i tried to save everyone she dominates with those masks, its a pain. I wish Larian would put some way to release those NPCs before the fight. I tried to steal the masks from them the first time, didnt show in the pickpocket menu.
As for the hag fight, the easiest way i found to beat her is to silence the area shes in, must be done before she summons aid and use her illusions, best way to do it is to change characters mid conversation and throw the spell with the character who has it before combat begins, my paladin did this both times and she became a walk in the park. I didnt had the potion bug though, worked just fine, luck i guess.

i killed her before the fire and they just bugged out... their fate is coded