Task Cold Hard Cache Bugged

I think I know how I broke it. I did not have the mission active, so I drove the Nomad down into a valley where the pirates with Hydra's attack you, not knowing it was part of the mission at first. Then I heard my crew say something related to the quest about them. This happened before I secured all of the cache's first. So I beat them all and looted everything I could find. My quest still shows that I need to interact with one more cache (it's close to the battle I just described) but I can't do anything to this cache. I am now blocked on this mission.