I’m curious about the naming you use. Will you screenshot a couple of albums?
For example Beethoven is the composer but not the artist, which might be The Academy of St. Martin in the Field, or The London Philharmonic Orchestra. Are you letting Picard do any tagging?
Plex is really quite terrible for classical music - it does not support any of the useful tags Composer, Conductor, etc, nor does it support multiple artists, so you can’t use Album Artist = “Ludwig van Beethoven;Herbert von Karajan;Wiener Philharmoniker” as a workaround either.
Only practical way is put one name (the composer) as Album Artist and any other names (conductor, orchestra, etc) as Track Artists - which is not really a great way to do it and will screw up other music apps that do support all those tags correctly, but at least it will group all Beethoven symphonies under the Beethoven artist.
Are you sure? My classical music that I have tagged using mp3tag and assigned the Composer tag to appears to group everything together well under the composer. I then have used the Conductor / Orchestra as Artist.
This is likely through matching with Musicbrainz (which has the composer as album artist), you can see that by changing the Composer field to another value and rescan - new composer won’t be picked up.