I have never done a Restore, however since you only have one file…how about trying a stand alone copy/paste from your backup device. Open the directory tree using Explorer (Win) and point to your device…F:, H: or whatever. Expand the folder of “WD Backup.swstor” then expand and drill down to a weird folder (some strange character). You should now see a History and a Volume (…) folders. The Volume() folder should contain the latest file that you last backed up. The History folder has the multiple copies and has a stranger presentation of file names…hope you don’t need one of these. Copy and paste the desired file back to your PC folder. Use the date sort to find you files.
As to your Restore, I hope you post back your findings on this issue.
