Please don’t fill in the album tag if the album is unknown.
- is this library actually using the “Plex Music” scanner and agent?
- If you go back to your 2nd screenshot above: the fact that the artist name appeared in the input field for the album title gives me the idea that something about your meta tags might be “special”. Is there a possibility that the file contains more than one type of meta tags? Or that one meta tag contains more than one value?
Either way. A future PMS version will bring some revamped scanner and agent code. It is worth revisiting this issue again after that.
If you have a spare machine or a VM, you could try this preview release (do not use it on your regular Plex server!) [Plex Media Server] Forum Preview for Music Metadata