I had just defeated the LU-74 Firebug boss in NG and ran back to the medbay for a safe area save. I came back a day later, ran to the place where I killed the Firebug, and the boss is still there. You can hit him, but the hits don't injure him. Therefore, I'm unable to move forward in game progression.
It's a really unfortunate bug as there is no way I'm restarting my progress in this game. In all likelihood, I would ditch the game and rate the game fairlt poorly regarding this game breaking bug.