Apple Music Error When Adding Song to Playlist
Apple Music has a nice "feature" where if you have a playlist you didn't make downloaded on your computer, Apple Music treats them as local files and gives you this error when you try to add one of those songs to your own playlist.
Cloud Music Library playlists can only contain songs from your Cloud Music Library.
The workaround for this is to remove the download of the song you want to add to your playlist. @Apple take a look please?