Removing Hidden status from album art?

[Terry Pinnell]

I'm trying to tidy up the 'album art' in the My Music folder. Many of
the images, all named Folder.jpg, have greyed thumbnails, and have a
greyed checkmark against Hidden, in Properties. Why is that please?
And how do I uncheck it?

 

[Terry Pinnell]

I'm trying to tidy up the 'album art' in the My Music folder. Many of
the images, all named Folder.jpg, have greyed thumbnails, and have a
greyed checkmark against Hidden, in Properties. Why is that please?
And how do I uncheck it?

No one with any advice on this please?

In fact *all* album art in My Music and its many subfolders is the
same. Hundreds of files with names like
'AlbumArt_{317AB331-FAE8-4F2B-8575-0E315184FAB1}_Large.jpg'

My question is simply: how does a file get this 'Hidden' status and
how do I remove it please?