So I went to Xur, and for the third week in a row, he doesn't have the exotic cipher quest available for purchase. It seems like my account got bugged, as I most definitely do not have a cipher in my inventory, nor do I have the quest, but it's still not available. And it's not available not in the sense that it's there but greyed out and disabled, but it's not actually visible at all. It's as if the exotic cipher system just doesn't exist.
I assume the reason for this is because I purchased and then abandoned the exotic cipher quest a couple weeks ago. My wild guess is that the system thinks I still have the quest despite abandoning it and it not being in my quest inventory (or on the abandoned quests kiosk thing in the tower either for that matter).
It'd be really nice if someone from Bungie could take a look and sort out whatever is flagging my account like this.