I have been trying to complete the mission that requires an obsidian crystal for months. And finally when I had the Rare bounty I wasn't able to complete it because it required a full armor set from the black armory... Is Bungie able to "give me" another Rare bounty or even the Obsidian crystal?
when you go ta Ada buy and finish 2 weekly and daily task. Repeat second week.
Remember that you need place on tasks inventory because bounty from Ada come to You tasks list.
Max task limit is 63. If You not over 60, bounty come to You.