File Transfer Success, All Files Missing

So I've got an odd question, though not sure how to word it so please bear with my rambling of the "issue".

I backed up data from a user directory (robocopy, /copyall) and it worked wonders. After instillation of Windows 10 I attempted to transfer the files back to the HDD. The transfer was from an external HDD (Backup Drive) to the Win 10 HDD through a Sata/IDE connection. The restoration of data from backup to the Win 10 HDD was using Windows 7 (may be irrelevant). After 2 attempts the transferred data was confirmed (via Win7) on the HDD but whenever the drive was booted from all the data was missing; as in the data was free space, and appeared not to have even transferred. The third attempt I directly connected the backup to the Win 10 PC (Live at this point) and simply drag and dropped. This worked no issues.

So with all that said, what would have caused the lack of data transfer after the drive was disconnected? (Almost like it was write protected..)

Not too important but I'd love to understand where I made a mistake;
Thanks in advance for your time and help!

There is another thread here about a member that Robocopy says that its copied all files, but they are actually missing.

Caledon Ken said:

Do you have a link by chance

cant´find it!

Do they copy as shortcuts and not the files themselves? In which case, when the drive goes, there is nothing to shortcut to.