The AI does stall after running out of ammo for their siege weapons. Is that a bug?
Likewise. If you see your AI oppenent attempting to siege your castle with no other siege equipment but a mangonel, we highly recommend that you auto-resolve the battle. For after the AI has run out of ammo, it will simply stall, forcing you to have to exit the settlement to provoke action or exit the battle or wait until the battle timer runs out. Edit: Issue never happenened in my testgames, probable a solved older bug.