Uniti Core Backup - replay on other Naim Equipment

I have backups of my Uniti Core on a NAS Drive (Synology) and also on a 2TB SSD drive, which I keep up to date. I believed that I could take my SSD backup to my French property, where I have a Uniti Atom, and use it to listen to my music collection via the USB input, but I just get ‘no result’.
How do I create a copy of my Unity Core on a portable SSD that I can then take abroad and listen to on my Atom? The music was all ripped as WAV files, but I am not that fussed about the metadata.

Ideally you want FLAC, not WAV, but the WAVs should still play. It’s just that the metadata may not be visible. I wonder if the drive you use was formatted correctly?

Have you examined the files on a computer to check that they are intact?

Are you able to connect the SSD to a laptop/computer successfully and see all the contents?

Strangely enough, I was able to see it on the computer when I first created the backup, but having just retried this, the SSD does not appear!! Could well be the issue. Thank you