are you seeing that message with every track or just some?
I'm seeing it with every track I've played back today. It was working fine last night. Now, it happens with some tracks.
This is a track which doesn't work:
Opening track for playback: "D:\Music\A Split - Second - Flesh (1991 Remix)\05 A Split - Second - Flesh (Slow).flac"
Audioscrobbler: Submitting track...
Audioscrobbler: Submission succeeded.
Last.fm Playcount Sync: Contacting Last.fm....
Last.fm Playcount Sync: {"error":6,"message":"Track not found","links":[]}
This is a track which works:
Opening track for playback: "D:\Music\Aphex Twin - I Care Because You Do\09 Aphex Twin - Mookid.flac"
Last.fm Playcount Sync: Contacting Last.fm....
Last.fm Playcount Sync: Last.fm responded ok. Attempting to update playcount...
Last.fm Playcount Sync: Playcount updated successfully.
Audioscrobbler: Submitting track...
Audioscrobbler: Submission succeeded.