I've gotten this bug a few times now. Only place i know for sure it happened was at the brothel.
Boris, armed with a shotgun and wearing helmet + body armor.
I put him in cover to fight the bandits at the brothel and if he gets shot he freezes. Cant move or shoot. Tried going into scavenge mode and clicking other objects, nothing will get him "unstuck". The last time it happened the last bandit ran out of ammo and ran, so I could spend time trying to get him unstuck.
Possible this only occurs if he goes into "wounded" state.