All the ones I was missing suddenly unlocked themselves - I assumed this was Bungie doing it after realising they were unobtainable, but if this hasn't happened for everyone then it might be related to where I'd got to in Petra's quest line and they might unlock for you if you continue through the quest, especially given the following: [spoiler] completing this quest line unlocks a small amount of weekly queen's wrath bounties that also include wanted bounties. [/spoiler]