I am a Spotify Premium user but the Download/Available Offline toggle button is not found in Songs list on my desktop.
However, the toggle button is found in the playlists that I follow and also on my iPhone. I believe my desktop has been removed from the Offline Devices as only my iPhone is in the list of offline devices.
I have tried reinstalling Spotify but it still didn't work. Would like to know how to fix it as I'm not able to listen on my desktop when I don't have internet connection.