Sooloos format is incompatible with PC format that is why you can't see it, you could use Duncan's Sooloos interrogator program to to read the copied disk and check what is backed up, or you can run the Sooloos backup program from Control:PC.
Personally I moved to Roon where all files are kept in native format and so can be read by PC or Mac, Sooloos encrypts the files.

Russ