Sometimes AcoustIDs will exist and be linked to a Recording MBID but AcoustID.org does not (yet?) have MusicBrainz metadata for it. E.g., right now as of this writing https://acoustid.org/track/f13cc39a-f975-4b86-9f2a-315d72f16184 does not have this information (archived version). This results in AcoustID scan-lookups properly returning the Recording MBID but no additional metadata, which makes Picard file all of the resulting files under [non-album tracks], which can be confusing (see e.g., this chat exchange).

It would be great if Picard could recognise that no Release metadata was received and look this up itself.