I've noticed in the last couple of weeks my spotify PC desktop app no longer scrobbles to last.fm. I am connect to Last.fm in the settings - it shows "connected to last.fm as xxxxx". My android app and iPad spotiffy app's both scrobble fine using the same credentials.
I changed my password on last.fm and updated my password in Spotify settings. Again, last.fm connectivity shows "connected to last.fm xxx". This still hasn't fixed the problem as the desktop app doesn't scrobble, yet Android and iPad do.
To try to remedy the problem I uninstalled Spotify desktop completely then reinstalled it, however, this hasn't fixed the problem.