The area trigger is just outside the Main Operator spawn point.

That is not a bug its an area trigger I placed to spawn the AI once the good guys enter an area. I should have placed another trigger to disable it. It depends where you start .

https://imgur.com/a/MavArix

after I cleared the whole map, the mission didn't end, so I had to backtrack and clear everything again. watching the replay in dev mode I noticed that this guy spawned in towards the end. not sure if it's a game bug or something with the map. maybe it's something you can fix?