How to add playlist songs to "Songs" category?

Hello everyone,

I'm not sure if there's a post for this already, but I am having trouble adding songs from playlists to my library. I have added a bunch of playlists and the song library does update with songs, but there are still so many songs that do not even pop up. I tried deleting and re-adding a playlist, but the songs are still not in the "Songs" section of the library. There is an Apple support thread with a similar issue that recommends turning syncing off and on, but this did not help. I also made sure to toggle the "add playlist songs to library" option on all devices.

Does anyone have a similar problem or know how to add all playlist songs to the song library?

Thanks!