Well I found out why I was having issues with my old WD Black 4TB drive.
Started to move over some of the backed up stuff to find out that loads of old files are now unable to be read, Windows Scandisk says there is an issue and then gives up.
So I am in the middle of copying everything I can off of it while I can.
Its starting to dawn on me that I am not having much luck with hard drives LOL.
*** update ***
Seems I have lost 1.74 TB out of 4 TB so far
Mostly consisting of Games, Programming, VM (Virtual Servers), Media Content.
The Games I can just re-download, Media Content I have on Discs so these two are fine.
However the Programming and the Virtual Stuff are gone for good, I am hoping some of the other programming backups also contain some of it, in fact I might have all of it, not sure yet.
But it seems that everything that I have written within the last several weeks are missing / broken
It could be worse it is a 4TB drive.
*** update 2 ***
I might actually be ok, it seems that the USB to SATA Caddy only supports up to 2 TB Drives, hence it telling me I had lost 1.7 TB of data.
I made a SATA Data and Power Cables and connected the drive to that and now going through the Chkdsk, well its been going through that for the last several hours and it says its only got about 30 mins left, so lets hope its all fine.