"Playlist can't be added to your iCloud Music Library". Why? I am migrating from Spotify and I want iTunes to accommodate the way I used to add songs to a "favorites" playlist, just like the Starred Songs works on Spotify. 

Initially I created a Smart Playlist to self-update with all my hearted/loved tracks (let's call this Playlist 1). That didn't work because apparently the heart rating doesn't persist between devices, and most of the point of this is so I can have this self-updating playlist available offline on mobile. 

My second solution was to create a non-smart playlist and manually update that one with any new music the smart playlist catches. (Let's call that Playlist 2.) That works (I can set this manual playlist to be kept accessible offline on my phone), but it's cumbersome to manually copy-paste songs every time I heart new tracks. 

My third solution was to create another smart playlist especially made to mirror the first. (Let's call this Playlist 3.) The first playlist is set to auto-add any hearted tracks, but since this parameter doesn't carry to mobile, I made this second smart playlist that simply adds whatever music is added to the first. Essentially a mirror playlist, but with a different parameter. 

This kinda works, but I get a strange error: 



The playlist was created, and it works as I intended (successfully mirroring the first one at all times), but apparently I can't access it from other devices for some reason. 

Why does this happen? The Playlist 3 contains exactly the same tracks as Playlist 1, so the given reason that Playlist 3 "includes other media kinds or songs that are not eligible" doesn't make any sense. 

Anyone knows why is this happening and/or how could I solve my initial problem?

Thanks!
"Playlists that reference other Playlists can not be uploaded"

It took me awhile to figure out the solution to this problem, but I eventually did. You can no longer just drag and drop songs from Apple Playlists to new ones that you create yourself, but you are still able to do it a different way. You also used to be able to just right-click on a song, a menu would pop up, and you could then "add to selected playlist" - this no longer works either. 

Solution: if you go into any one of your Apple Music playlists, hover over any one of the songs, you will notice a little icon with 3 dots show up - if you LEFT-click on this, a menu will pop up (different than the old menu), and then add the song to your desired new self-made playlist. This seems to work.

The problem is that iTunes still has both the old method and the new method active, but only the new method actually works.