Here are some possible solutions!
1. Restart your console
Restarting your console will ensure that any achievements awaiting synchronization on the console are re-sent to Xbox Live.
To restart your console:
- Press the Menu button on your controller and select Settings.
- Select Power & startup, and then select Restart now.
- On the Restart your console screen, select Yes.
If you can't restart your console this way, you can also restart by following these steps:
- Press and hold the Xbox button on the console for at least 10 seconds, until the console shuts down.
- Press the Xbox button on the wireless controller to turn on both the controller and the console.
- Once youve restarted your console, allow up to 72 hours for the synchronization to take place.
2. Remove and redownload your account
The account information stored on your console may be out of date. To update your account information, delete and then redownload your account. Here's how:
- Remove your account from your console.
- Restart your console following the steps listed in Solution 4.
- Redownload your account to your console.
If these steps do not help, please contact our Ubisoft Support for further assistance! Thanks!
http://support.ubi.com