I've been trying for the 'one with the shadows' achievement by doing the additional thieves guild missions (fishing/bedlam/heist etc.) and have unlocked the additional quests for Whiterun, Solitude and Markath, but I have been unable to unlock the final one for Riften despite having done in the vicinity of 20 of those additional thieves guild quests in riften. Have I broken it? Is there a console command to trigger it? I assume Delvin is the one who will give me the new quest (as he started the prior 3) but he just keeps offering me normal work.

*edit* Nevermind, decided to use my brain and worked out it was the other town Windhelm, which I hadn't done enough side missions in. Fixed that, got the Windhelm special mission and now have the achievement hurray!