you for reaching out to the Community regarding your issue, although I am sorry
to hear that you are experiencing issues with your mobile sync. I apologize for the late response. I'm wondering here to prevent the issue from happening again one thing that we can do is with the sync on make sure that all accounts aren't selected. This should prevent the issue from happening again.
First you may want to save a backup incase of any errors. You can do so by going across the top to file > Copy or Backup file > Create a complete backup.
To do this you'll want to activate the sync by going across the top to edit > preferences > Mobile & Web > Sync On. From here once on you'll see right below it is accounts: (x) of (x) eligible accounts enabled. Click on this blue section and it should bring up all of your accounts. Make sure all of them are deselected. Once this is done it should sync and you should be able to turn the sync off again. It will remember your previous settings if it were to turn on causing none of your accounts to sync with the cloud.
Ideally after this we shouldn't have any more trouble with the cloud. If you have any questions please let me know so we can take a look.