Stats not transferred over from 360 to one

So back on the 360, I mostly played reach and halo 4. When I made the switch to xbox one, I downloaded the games from the backwards compatibility program. I noticed that my stuff was all reset back to rank 1. This has been this way for years, but I just assumed it was nothing. I recently went on my 360 to see my rank, and it was all gone. My rank is still the “new” rank on xbox one, but my rank on 360 is back to 1. Any solutions, or is years worth of work gone permanently?

Have you tried redownloading your profile?

Before the first time you hopped onto Halo Reach/4 on Xbox One did you change your Gamertag? Also, are you able to search up your old GT on HWP or Legacy Halo tracker to see it’s stats?

Very limited on what I could do to help you, this is something that someone from 343 would have to look into. Best of luck