As stated in the title, there's a siege tower bug when besieging castles. At the end of the push when the siege tower docks onto the castle wall and the front segment that comes down is down, your men or allies will get stuck on it and will be unable to move from that location. It's really frustrating to deal with as you have to rely on the unstuck soldiers to do all the work instead of the 20 or so that are stuck.