Guild Wars 2

So i was in the lord room of Stonemist Castle when i see a Ennemy thief run and enter in the wall. He started to attack guard from inside the wall, which no one was able to kill him, i manage to target him. So, i dont think running inside a wall is normal.

(sorry for the bad quality of the screenshot)

So today i was doing some WvW on Eb, we was sitting on SMC siege for the incoming zerg when we saw a thief pass the wall like nothing. He was glitching to pass the wall/door with some X reason.
The wall was never being down till 3 hour ago, and we held the SMC from 2 day. The thief was attacking our siege and disrupt everything…

(sorry for the bad qualities of the screenshot)