I have a Halo MCC achievements that have been stuck at unlocking for around 5 months. The achievement is Sightseeing. I have tried all the solutions listed here multiple times with no success: http://support.xbox.com/en-US/xbox-one/games/troubleshoot-achievements-challenges
Are there any other options to get this achievement to unlock. Its really bothering me that its taking up one of the six closest achievement slots.