Halo 5 Skulls

ive collected all the skulls in game as referenced in my career service record. However, when looking to the achievement section for Halo 5, it says the Gravelord achievement is 92% done. Any help would be appreciated

So Xbox is weird when it comes to this. Sometimes it’ll have a sync error and won’t give you the achievement until later. I remember getting an achievement for a game I haven’t played for months due to the sync error. There are some work arounds. Some say do the objective again so in this case maybe grab a skull again. Another is complex and I recommend googling it but it revolves force syncing Xbox. I’d tell you but I can’t rememebr everything off the top of my head. Hope this helps