[Bug] Quarrite Elimination Mission

I was hosting with my friends and we were doing the QUARRITE mission Elimination when my game locked up then my PC restarted. We were up to finding the last tunnel and had to kill the bosses x 2. When we continued on and got to the mission point marked with the detector nothing happened. We tried everything we could think of and even though the detector said we had reached the point it wouldnt tick it off the list like the previous ones did. No bosses appeared, nothing. We tried reloading and travelling quite a distance away and back to see if it would work but nothing. I havent experienced bugged missions like this since the game first came out.