I recently found that when I play tracks on Spotify from my desktop, my last.fm does not scrobble the tracks. It does seem to recognize the track, as the track I am playing shows up on the last.fm website, but after the track ends, the scrobble is not recognized.
Solved! Go to Solution.
Had the same problem until recently.
"Last.fm staff have confirmed that Spotify's internal scrobbling is dysfunctional on the newest desktop Spotify (version 1.0.80) and it also seems to be the case with the newest update of the Android app.
I suggest connecting Last.fm's scrobbler app to your Spotify account. Read this last.fm announcement for more information and guidance."