Weird metadata issue with music

[mjdbb1 7]

Hi all.  I'm having a weird issue with metadata on music files.  My library is set up with no issues and I've cleaned up and locked some metadata.  I'm running the latest version of emby on an older intel nuc.  I occasionally like to make a whole disk image backup so I shutdown emby, move all my music (and other media) to an external drive.  I do this to cut down on the size of the image backup.

When it's done, I move all the media back and then start emby server up again.  However it seems to then go through my music files and makes some changes that I don't want (even on locked items), for example it will go and add album artists to singles and make them look like whole albums, which I don't like.

If emby server is shutdown while I'm moving things around, what's causing it to mess with my metadata the next time it starts?  This doesn't happen unless I move the files around so I'm a little confused.

Appreciate any help!