During the siege of yesterday, attackers broke a part of the wall left of the gatehouse.
Problem is, when the wall went down almost to the ground, attackers couldnt go past an "invisible wall" because from their side, the wall was still there (visually too!); from the defenders side, there was no wall and they could freely pass from the castle to the exterior: it functionned like a postern but it clearly is a bug of the map.
I'm pretty sure that using the catapult anywhere on this castle would have the same result, hence an impossible to breach castle (except with ladders and siege towers).
The design of this castle is already very defense-friendly, and I'm glad that our Ni/imperiale hold it, but this bug is wrong and gives defenders a very unbalanced advantage: rework the walls so they can be breached.