Enable “Prefer local metatags” in the properties of your music library.
Warning: doing so will wreak havoc in your library if your folder structure and the embedded meta tags are not in immaculate shape.
Most important: there is a difference between the “Album Artist” and the “[Track] Artist”.
Plex uses pretty much only the Album Artist.
The folder structure must follow the Album Artist.
https://support.plex.tv/articles/200265296-adding-music-media-from-folders/
Example for a sampler album. Notice the folder name following the album artist meta tag.
Example for a multi-disc album. Notice the presence of disc # meta tags and the presence of both Album Artist and Track Artist meta tags.
The Album Title meta tag has identical content for both discs!
