I noticed the same thing. I finally spotted him. He’s on the roof of the building above the shd tech. I think he only spawns after 22:00, and anytime there are friendly npc’s around he doesn’t seem to spawn. Unfortunately I didn’t have any special ammo when I finally spotted him, so I didn’t kill him, but he takes off if he spots you. It’s also possible he doesn’t spawn if you control the control point west of the location, and it’s possible he doesn’t spawn if you don’t have the demolition spec active. Let me know if you figure anything else out.