"Songs" not available for offline sync

[jebaloo]

I recently noticed that whilst selected Playlists can be made available for offline listening, the "Songs" category navigable under "Your Library" no longer has this toggle button visible.

I don't use playlists relaly... I just add songs to My Library, and I need them to be avialable offline, as they always used to be.

I've already reinstalled Spotify etc.  "Download" button.. not visisble here, see?