Playlists on desktop app: here today, gone today

I have two self-created playlists on my Sonos desktop app (I have S1). When I try to add a song to one, I get the message “No playlists have been added to your Sonos Playlists yet,” even though the two that ARE there quickly flash before that message appears. Then I try a few more times and it works. Then it doesn’t. Quite frustrating -- anyone else have this problem with the desktop app? I know many have complaints about the mobile app. Thanks!