Title says all, for some odd reason, in the cave that leads back to the room where the guards and marines were having a fight, the Vortigaunts are bugged and unable to shoot their bolts for whatever reason. They do try to fire them at me, but the beam never shows up, and as soon as I lead some of them out of the cave, they're able to shoot their beams again.

Image:
https://imgur.com/a/ekRdv