As I said, the new Plex is easily confused by compilations, and now it just doesn’t know what to do. 
I would try going to your new, improved Various Artists page (the Spencer Davis Group), and use the fix match option. You find that at the top of the web app - the three dot thingy. You have to be at the artist page, it won’t work from any of the albums. Select the first choice, or the one that says, “Various Artists - add compilations to this artist”.
If that doesn’t work, try un-matching the artist first, then matching the same way as above.
If that doesn’t work, you’ll likely have to learn the PLEX DANCE. I think you can skip step 4 for music files.
