AI enemies don't react on player or companions, they (enemies) can't detect you at all (detection marker not appears at all), you can't point them, but you can still see red crosshair on enemy. That not happened on this outpost for the first time, it happened after activating "Outposts (master)" (or something like that, I have russian version of the game, so I don't know how it's called on english) in pause menu. Some additional info - the story was fully completed, this bug not appeared on other outpost, but I tried to return on bugged outpost again and AI was still broken here.
Upd.: game restart not fixed the problem.
Upd. 2: Player can run away from outpost after clearing it until notification appear (something like "Capture the outpost", notification with sound effect) and run back to the outpost to capture it.