This happens occasionally, for the past couple of years across different devices. I’m currently online, streaming music from the web on a stable connection. I am attempting to add a song from one currently playing playlist to another. When choosing what playlist to add the song to, nothing at all happens when tapping on the desired list; no error, nothing at all. The only option I have is to cancel and go back to the current playlist / now playing. Trying again does not resolve. Only way to get out of this bug is force closing the app and rejoining. This happens on both iOS and Android OS versions of the app.