Errors uploading a playlist to iCloud with Apple Music

I'm getting the classic 'Not Eligible' for iCloud upload messaging on some of my playlists :

"iCloud Music Library playlists can only include music from your iCloud Music Library. This playlist can’t be uploaded because it includes other media kinds or songs that are not eligible."

I've referred to the document regarding eligibilty : iTunes Match: Understanding the iCloud Status icons - Apple Support and have narrowed down the problem to songs that have been added to the playlist directly from Apple Music. If I remove any of those songs from the playlist, the playlist shows up in iCloud. This seems like a pretty bad bug, or am I misunderstanding something? I'm on the latest version of iTunes 12.2 and Mac OS 10.10.4