[Zubersoft]

You can certainly try to use the companion to see if you get better results. First, reboot the Samsung device (and the Kindle) just to rule out any files being locked. Then, install the companion app on your PC (https://zubersoft.com/mobilesheets/compa...hp?lang=en) and on the Samsung tablet, tap the three dots at the top right corner of the library screen and then "Connect to Companion". Select File->Backup Library, and this will generate a backup file in the folder you selected. Now disconnect the companion, and repeat the steps for the Kindle. Now select File->Restore Library and select the .msb file. Hopefully this time it will all go through without any issues. 

You could also try creating another backup after a reboot and repeating the steps through Google Drive and OneDrive. It's possible that may address the issue as well.

Mike