I've seen some inconsistency in tracks being scrobbled lately. I will listen to an album, and not all the tracks will show up in Last.fm or ListenBrainz.
It could have something to do with some of the app/playback stability I've been seeing lately where I've needed to force close the app to resume playback (I'll file a bug for that one as well). I'm guessing that pending scrobbles are lost in a crash/force quit.