I acquired the Forerunner sidearm and completed the quest, but when I went to claim the 30th Anniversary Triumph for the seal, it said I hadn't done it yet. When I went to the quest archive kiosk in the tower, I could pick up the quest, which said I was only at step 3/6. However, that step requires me to get the key from Xur, but I can't acquire it for a second time. So, here I am, literally holding Forerunner while the game tells me I don't have it yet. Can someone please help? It's clearly bugged.