So I was playing a couple nights ago and realized I was not longer seeing progress made towards the Heroic co-op achievement in the achievement app, although my co-op partner was. I then tried to get a couple of the miscellaneous achievements I had yet to get (10,000 points/Par Time on Score Attack, complete mission on Heroic with 3 skulls, ground pound grunt + grate on Battle of Sunaion, etc.), and none of them were unlocking. Basically, there is a variety of achievements and nothing was unlocking or having progress made in the achievements app.
I’ve had since hard reset my console, to no success. I have deleted local save data, nothing. I have even tried reinstalling the game to no success. I even deleted my XBL Gamertag from my console and downloaded it again when prompted by the game to select a profile, and that actually made the situation worse; now, all my achievement progress is stuck at 0%, even if some of the achievements had some progress before (such as original Warzone map wins).
This issue is unique to Halo 5. I have been able to unlock achievements in other games on the One, even if I immediately switched to it after attempting to unlock an achievement to no luck in Halo 5. Is there a solution to this problem?