In the normal Arc, the objectives are "Search the Safe" and "2 Collect Automaton Remains"
One of the automatons is a Manticore outside the base, and a red objective marker leads you to a stone door into the base proper which houses the safe. Once the safe is activated, a Positron Automaton ambushes you, and killing it ends the mission.
In Ouroboros mode, The red objective marker does not appear, and if you have never done the Dark Watcher arc before (Or just forget), you basically will never, ever recognize the door as significant. This occurs for others and not just me.
Another minor bug is that the map is mis-aligned, but I use Vidiotmaps so this may be a personal issue.