Just added last.fm to both Spotify and Sonos. Problem - scrobble not happening when songs are played through sonos speakers in any situation. Spotify connect to sonos, Spotify initiated from Sonos controller. Sonos controller initiating other music services.
On spotify app - if I play on my computer, it scrobbles. Then if I select sonos speakers, subsequent song don't scrobble. It just sits there on the last song that was playing when i switched to sonos. Reverse happens too - if I start on sonos, no scrobble. If I switch to sound though my computer it immediately starts scrobbling.
I've tried removing and adding the last.fm service from both sonos and Spotify and trying it in every configuration I could think of.