I've recently come across plenty of enemies in FSC that tend to "hug" walls or other enemies they are spawned with, and sometimes dont even attack until hit, up to 10 mobs can be effected by this bug
Picture evidence via steam can be provided if needed
I've seen Trojans doing it too. I'm hazarding a guess that it's the AI telling them to move in one direction, but because of the wall they can't. So they keep attempting to walk in that direction.
It happened with me with a Howlitzer head. Hilarity ensued.
This saved my life in FSC. 2 Zombies blocked a Trojan in the mini arena with a health pad. I even had enough time to set a tea party there~
that not a bug -_-
because zombie have no brain =]
yea.. it supposed to be not smart