So previously I had (and still have) this issue with halo wars 2, I just completed the campaign for Halo Wars 1 and not a single achievement unlocked, both games show no progress on the xbox app. I own the games and played them through the xbox app/microsoft store.
I tried reinstalling the games and xbox app, launching the game through microsoft store instead of the xbox app, signing out and back into my xbox account and even installed the games on my laptop to see if the achievements would pop up if I play on a different system, to no avail.
I’ve looked everywhere for possible solutions that I haven’t yet tried, but found nothing.