I have completed the Tides of Vengeance story line/quest line, up until “A Gathering of Foes” (when Sylvanas accuses Baine at Warfang Hold). However, while the other chapters/requirements for this achievement completed as I progressed the quest, the “Mischief Managed” part for some reason did not turn green. I still played through the quest, including the “He Who Walks In The Light” portion and beyond, but it never satisfied the “Mischief Managed” requirement.
In retrospect, I believe I triggered the Gossip/“Stay a while and Listen” with Halford Wyrmbane right before turning in Mischief Managed (so while I had the quest from Jaina to talk to him, instead of immediately handing in the quest I triggered the Shaw/Wyrmbane conversation). It allowed me to turn in the quest after the dialogue but I wonder if that may be what caused the trouble with the achievement.