Preview update deleted my old achievements

so today 04-12-2016 i updated my console.. after the update i noticed something about my achievements there are points gone for some reason, after looking in to my games list i saw that all my achievements starting from 2005/2006 are missing these are all
xbox 360 games. How is this possible? And why did it happend?? I'm a good gamer i never cheated or something like that how did al my hard work just dissapeared with one update? Please help me out to find the problem i hope this can be fixed soon!!

:)

 

2 different issues

So I've had 2 issues since the update. one, my achievements are not popping at all and it's not tracking any of my progress towards my achievements, I've tried deleting and restoring my profile, opening my nat, hard resetting and so on and nothing has worked.
Secondly ever since I deleted and reinstalled my profile, my wwe game wont fully sync, it will go to 46 and stop, I've tried deleting and re-downloading it but it does the same...

Side note: I've seen on others posts, that you say only the people with the preview program have the update and they say they don't. I was also told I have the preview program, which I don't and have had the update and same with my friends they have had
the update and no preview program.

 

If I Purchase A Game In Game Preview Are There Achievements And Save Progress?

Here is the released achievements for elite dangerous

Elite: Dangerous Achievement List

the game will get a full 1k either with updates to the preview build or when it comes out of preview and is a full release

 

this is a picture from trueachievements, my gamerscore was 26,498 (maybe more) and now it is 14.995

 

You have probably had a gamerscore reset of your Xbox 360 achievements. You should be able to find out more about this at enforcement.xbox.com.

Gamerscore resets are issued for cheating or tampering with the achievements. Likely problems include having online-only achievements "unlocked offline", for example the Halo games' Vidmaster challenges and Gears of War "ranked" achievements. If your gamerscore
has been reset, you have lost all 360 achievements you had at the time, even those unlocked legitimately, and will not be able to unlock them again on this gamertag.