Offline playlist doesnt update

Hey

I have selected the download button for a playlist. I want all titles to be available offline. It did download all title. But no when I add a new title to the said playlist, it isn't downloaded. The playlist is still flagged "off line" but new titles actually aren't available online. 

I tried removing and adding them again, opening and closing the app, nothing work. The titles are added but aren't downloaded.