Okay, I’ve tracked down what’s going on here.
As the Premium Music libraries are now using the standard music agent (the new music library update isn’t quite ready yet) the naming structure for files without embedded metadata is different.
These libraries should be considered standard music libraries now and as per that spec, the naming should be as follows (https://support.plex.tv/articles/200265296-adding-music-media-from-folders/)
Embedded Metadata is Not Present
In the absence of embedded metadata in your tracks, the file naming and organization are both very important. You should name and organize the tracks as follows:
Music/ArtistName - AlbumName/TrackNumber - TrackName.ext
By naming it this way it will get matched correctly.
Alternatively, you can use a format that has better tagging support, like FLAC, and make sure your files have embedded metadata for at least the Artist and Album fields.
The upcoming improvements to the music libraries will also make make matching a lot more effective and shouldn’t require you to make changes to your current workflow, however as mentioned this update isn’t ready yet so for the interim the options are the two I’ve listed above.
I hope this helps!
