[Zubersoft]

It could just be a temporary issue with the connection between your tablet and OneDrive. It's very hard to say without more information. Nothing has changed in the app for quite a while related to the OneDrive connectivity. As a workaround, create the backup file on the device itself and just upload the file using the OneDrive app. If the upload is taking a considerable amount of time, it's also possible the oauth2 token is expiring and Microsoft's server rejects the connection from that point on. If it's very consistent, can you see how long it takes before the upload fails?  

Thanks,
Mike