Work you way through the quests and unlock each campaign progress item.
Once you unlock the Master Expedition (15 unlock) the achievement should pop for you.
If you get NO in game notification, (as i did) log out and log back in.
This should then pop in game notifications, and the Xbox achievement.
If you highlight each campaign tree item in game, it will list what quests need to be complete to actually unlock the item. If you find yourself in game with out a quest marker, double check campaign tree.
The tree consists of the following
Into the Catacombs
Expedition to the Twisted Caverns
Into the Twisted Caverns
Twisted Caverns Untwined
Expedition to Wyllowood
Expedition to Terminus
Expedition to Vanrakdoom