Music content is not found (Video is working fine)

On DSM 7, user Plex was abandoned. Synology forced us to change the name.
They further removed our ability to delete the user.

You can delete Plex.

On DSM 7, use PlexMediaServer.

The main release notes about all the changes are here:

A few PMS releases later, 1.22.3.4973, when DSM 7 became finalized, I was able to make the final change – which makes the PlexMediaServer shared folder visible so you can make backups.

It has all the same restrictions as the Plex shared folder with one additional —

If permissions get messed up, the installer is NOT able to fix it. It is the user’s responsibility.

That’s why I continue to insert the “no media here” warnings.