I just bought this game and I was going to install it until I saw a review saying that there's a bug that cause AI squadmates to stop shooting for the entire level.

This bug exist? if it does, is there a fix?

Yeah, it just happened to me, I found this thread because of it. Apparently going back to menu and continuing the game from last checkpoint instead of loading last checkpoint from inside the mission mission fixes it. So, instead of respawning, go back to menu and continue from last save.