- sync is working coreectly
- yesterday the sync with the app sucseed, today doing nothing
Could you be more specific, and perhaps post a screenshot to demonstrate what exactly does not sync? You are telling on one line that sync is working correctly, but on the other one that it does nothing, so it is not quite clear what the problem really is.
Si les données ne sont pas affichées, comment tu sais que la synchronisation s'a effectué ?
Anyway, if the synchronisation really works, but the data is not appearing in your account, then it very probably means that your device is associated with multiple accounts. It frequently happens for example when you reinstall the application, and inadvertently sign up a new account instead of signing into the original one.
Follow the instructions from the support document Data is Missing from My Garmin Account After Syncing to resolve the issue.