Where does Volumio get it's album names from?

This issue has been regularly discussed but I haven’t seen a solution to the problem caused when you edit an album’s name in mp3tag (for all tracks) but Volumio still manages to show the album twice, once for the old name and once for the new name.
For instance, an album had an upper case A in “and”, so I changed it to a lower case a.
I did an “Update” and a “Rescan” multiple times but the issue remains, it now shows one album with an “A” and a duplicate album with an “a”.
I’ve double-checked all available tags in mp3tag and Windows attributes, no capital A seen anywhere.
I thought I had found the issue when I discovered a %recyclebin folder in the root of the network drive that stores my music. I deleted that in DOS with the rd command, it’s gone. I emptied the Windows recycle bin but still, Volumio does this. I have loads of albums that I’ve ‘tidied up’ and are now shown multiple times.
So where exactly does Volumio search for its data?