Was playing with combat extended (1.6 dev snapshot) and Citadel mod.

Pawns automatically leave fortifications if they have some need or to do their work, even during combat, which makes using the gun bunkers (the ones that need to be operated) impossible. (Builder leaves the Bunker to go repair a wall that just got shot by a mech, etc.)

It works perfectly fine with non-fortified turrets like mortars. If a pawn mans a mortar or any other weapon which DOESN'T make them disappear from the map their AI doesn't break, since they remain drafted. Pawns in bunkers stop being drafted and they just... stop manning them.

Tried forbidding doors, drafting pawns etc., nothing worked. How do I fix the AI? I have no idea.