Why does google music on the web not sync the itunes playlists?

[AC Question]

Music Manager shows "Location of my music collection: iTunes." When I first uploaded all my music to play.google.com/music, google music on the web showed all my iTunes playlists. However, it doesn't show the changes to my iTunes playlists that I have made since then. In Music Manager -- Upload, I chose "Automatically upload songs added to iTunes" (and I have repeatedly clicked "apply," to not effect). I can't find anywhere that says to automatically update google music *playlists* (based on my iTunes playlists).