Following the app update, I am unable to add songs to playlists whilst offline.  Please could someone help?

I initially add all my "new" music to my "Starred" playlist (which is available offline).  As I listen to that Starred playlist, I sort music that I want to keep by adding it to other playlists on a genre and rating basis (i.e., I might add a good song to my 5 star playlist and I might add a good bluegrass song to my Bluegrass playlist etc.).  I unstar the songs as I go through.  In short, my Starred playlist operates as a holding pen for all the music and the other playlists hold the music I wish to keep.

I travel on the Subway system an fair amount.  Before the app update, I could add songs that I was playing offline from the Starred playlist to a different playlist even when undergound.  I no longer have the option when underground but the option reappears when I emerge above ground.

If anyone could help, I would greatly appreciate it.

Many thanks.

Ben