I thought mp3tag had some options to clean vorbis tags, but apparently not.
Your thread title suggests OGG files, but your screenshot says you are using Opus files. This is not the same. I have a hunch that Plex may not be able to read the meta tags from opus files yet, while it handles ogg files perfectly fine.
Try to perform the Plex Dance “light” (meaning step 4 can be omitted)
with the whole artist.
