A problem stealing from the super mutants camp

[Yozzer]

I got this quest as part of the mayhem "string" of quests. I have to steal from a super mutants camp, and it selects the one at Horizon where the plane is crashed. I have robbed it dry 4 times now and the quest is still unfinished. I have been to the top of the mast and killed the strong guy and robbed him, and also been in the strong room and cleaned that out. I am worried now a save is corrupt or something. Anyone else had this problem?

[Cryptix]

What's the wording on the quest exactly?

[BizarreMan]

You should have a diamond over the container you are required to loot.