Xbox One Achievements are fucked. For a lot of games they are not unlocking, they WILL unlock, but with a few hours delay. Don't worry about it, it will unlock in a few hours, or if you are unlucky it might take days. There are reports from other gamers it took over a week to unlock on other games.
The X1 system is simply fucked, lots of Achievements have a delay. But it will unlock, it just takes time. Courtesy of Microsoft.