Apple Music Smart Playlist not syncing correctly with iPhone

I've just created a very simple Smart Playlist that selects all my "Loved" songs. That's it, not referencing other playlists, not referencing any song outside my library, no nested rules. Just "Love is Loved" as a condition. The playlist on my computer shows 166 songs, but the same playlist on my iPhone shows 144 songs. I've checked for some of the missing songs on my iPhone and they are in the Library and I can play them on my phone, no problem. They just won't appear on that Smart Playlist. Any tips?

I have all the latest updated software as of today (Jan 8th 2019) both on my computer and on my phone. I have both Apple Music and iTunes in the Cloud enabled on my phone and on my computer. If I update the playlist name, it gets automatically updated on my phone as well. If I "like" a new song, that song gets added to the playlist on the phone too. It seems to me that only some songs that were already liked when I created the playlist that are missing.

Solution 1:

I can confirm that somehow my library was the one out of sync. Songs that my computer thought were marked as liked were not marked as liked on my phone.

Solution 2:

A song loved on your computer doesn't mostly show up as loved on your iphone, while a song loved on an iphone is always showed as loved on a computer version of Apple Music.

Solution is to first add the song to your library on your computer and then loved it. Then it's auto synced to your iPhone.