I am trying to sync my offline playlists to my Moto X 2nd generation phone. I added some new tracks today and it only downloaded one of them. So I followed the instructions for clearing all of Spotify's data off my phone to perform a clean install. After that, when I tried to sync the playlist again even fewer tracks had been synced than before. I then found a comment from a while ago saying that I should try moving the music to another playlist, but when I did that 2 less songs synced properly.
I made sure that I am not at the 3333 song limit, I only have a little over 200 songs. Additionally, my phone has almost 20 GB of free space. I also noticed that all of the albums that are failing to sync have their album title and artist greyed out on my computer.