When 'favorite' stars are toggled next to a song (this can currently be done from the Songs and Playlists views), these views should be updated. I suggest:

toggle star in Songs --> update Playlists view. (If 'Favorites' playlist is currently selected, it won't update to reflect changes in favorites until user views another playlist and switches back to 'Favorites'. In general, whatever playlist is currently selected will reflect old star values until updated.)

toggle star in Playlists --> update Songs view (so reflects the most current star values) and Playlists view (specifically 'Favorites' playlist--when 'Favorites' playlist is selected and tracks are un-starred, playlist should refresh so that these songs are removed.