So, I’ve played Halo 1 through 4. I had all in Halo 3 until they added even more. Why is it showing no achievements? This is the same account/gamertag since Halo 1, though the name HAS changed, its still the original account. When I look at my achivs on my gamertag, they are all there. Just zero here.
Edit/Correction: ONLY Halo 4 is showing. My tag shows the others minus 2 though.
Hey OP, changing your gamertag causes a desync with older games, meaning that you need to resync them again under your new tag. If you still have access to them and have an active Xbox Live Gold subscription, load each of the up and play some campaign / customs / forge / matchmaking. Everything should sync up shortly after that.
The exception to that is Halo 2, changing gamertags means your stats stay with the old tag. As the original XBL servers are no longer in operation, there’s nothing available to sync to / with