I just spent hours upon hours completing halo reach on solo legendary and I check up on my reach stats on here and it says I earned the achievement for completing it offline? Also it didn’t even give me the legendary pin, it still says I have it done on heroic? I never went offline what does this mean I completed it offline? Internet didn’t shut off too?
Go look at my achievements for reach and scroll all the way down, you’ll see the two achievements you get for beating it solo legendary.
You can still earn campaign achievements while not connected to Xbox Live, they simply sync up when you sign in. For some reason you must not have been connected to Xbox Live when you were playing and so it didn’t update your Halo service record, the same thing happens sometimes with Halo 4. The connection can suddenly disappear and you not be given a notification of it doing so.