Hey all, we're aware of an issue that is causing users' achievements to appear missing on their profile. At this time, we believe the issue should be resolved, and you should be able to recover your achievements by following these steps:
1. Please sign out of Xbox LIVE, then sign back in. If your achievements are not restored after this point, please continue to the next step.
2. If that doesn't resolve your issue, please try earning another achievement. If your achievements are not showing correctly at that point, please wait a bit, and then try again.