Please be aware that I wasn't aware of this issue until some months after it happened, so my understanding of the exact problem is mostly guesswork.
At my workplace, we have a ReadyNAS storage device that we use as a network drive. In March, I set up the OneDrive beta app to backup all our files onto the cloud so we could access them anywhere. A few days ago, I checked the One Drive account and found it to be mostly empty.
From what I can tell, the login for OneDrive expired, and the bilateral sync read that as everything being deleted, and so purged all the files on OneDrive. Is there a way to prevent this from happening in the future?
Have you tried to update on the latest firmware? Bidirectional Sync if enabled applies changes on both Cloud and NAS. You might have deleted files on the NAS that might cause for the Cloud to be empty, Maybe try uploading changes on the NAS option.
Also, contacting Amazon might help and other users as well might be able to chime in and provide this information.
