Hello, I have a problem of the same type:
Achievement: Throne of Bones I
completed but did not unlock: 06/08/2019
I have completed all achievements of collecting all skulls in Halo: CE, Halo 2 and Halo 3 campaigns, but the Throne of Bones achievement is 97%, and I have already put all skulls in and have unlocked all their respective achievements. I would like some help or suggestion. Thank you!!
- halo CE (07 August 2018) : you find last 2 skulls "fog"and "piñata" but the achievement of find all halo CE skulls unlocks in 15 August 2018.
- "Halo 2: Find and claim all Skulls in Halo 2." Here it is regular,you find IWHBYD as the same day.
- Halo 3 also is regular.
you miss only 1 skull not well synchronized, the achievement pop up, but it s not well synchronized on halo waypoint so it s surely in a day when you have played the game semi-offline,or near past updates, or with bad connection.
This enigma happened to me with one halo 3 skull, but i think you need to look up halo CE or the first skulls you searched for.
Actually there is no way for see which is the right one.