Best posts made by Natfire
I had something similar happen. For me I assumed it was because there was a NPC who was trying to help but not doing much so everytime I tried to open the chest another raider came and went.
To get around this I went for the other chests in the location and came back to that one last. By the time I got there the NPC that was stuck was waiting on me to help open the chest.
The only alternative I can think of would be to reload the game from a recent save (such as autosave).