Hi everyone, thanks for replying!
Okay - BlackRectangle, I followed all your instructions - firstly, and perhaps vitally, you said
"First go down to Folders and External SD Card and see if you can find the files there. It should have them in a directory tree, with folders and subfolders, like Windows.
If they are in the folders, then the Clip can’t find or can’t read the tags."
I booted into the standard firmware (instead of rockbox) by powering on while pressing << - in answer to your question, the files are not there. Not visible. On the card when I checked on my laptop, but the clip+ can’t see them. Says [empty]
I went ahead and changed all the tags just in case. Tried again. Still nothing.
Tried booting into rockbox instead - the folders are on the SD card - open up the folders - two of the three are now empty. Open them on my laptop - yep, the folders are empty. Its like the contents have been deleted.
Suggestions would be awesome!