Apologies for the basic nature of this, I’m a bit of a novice.
I keep all of my music on a Windows desktop using iTunes. When I set up my Plex (primarily to host ripped DVDs of films and TV programmes and other mp4s that I stream to my smart TV) I also directed it to my music files too.
I have since been playing my music files through my TV’s soundbar, using Bluetooth and the Plexamp app.
A lot of my metadata is all over the place on my iTunes. I have a series of compilations where each is named differently, so I went through them and made the naming consistent in iTunes using Song Info.
This metadata did not carry over when using Plexamp. It was still all over the place. So I researched what the issue could have been and I ended up prioritising local data.
This has now changed the artist name on all of my compilations to Elton John. I’ve no idea why.
I think I may need to change ‘Album Artist’ in Song Info in iTunes to Various Artists. But beyond that, I’m at a loss to explain what i’ve done.