Not updating after initial By File backup

I am using a My Passport Ultra 2TB with WD SmartWare which I used on my old Win10 pc. Having bought a new Win10 pc I have installed the WD SmartWare software on my new pc and executed an initial By File/ Folder backup.

For the past 3 weeks I have been actioning manual backups and the software has been stating that the Backup was accomplished successfully and with the tick. File History is set to 5 versions.

Today on viewing the Retrieve folder all the Folder/ Files are greyed out and none of the since modified existing or new files are showing.

Any explanation/ resolution please.