Unknown AlbumArtist showing in tag library for flac files with performer / composer

[new_bloke]

Thanks for the responses. I must say that the artist array seems to be focusing on a rather niche requirement - namely classical recordings. I'd prefer if it were either optional or configurable. Perhaps even the option to only apply this behaviour to specific genres. For now, I'll just update the affected files with a specific album artist tag.
At least I am reassured it's not me doing something wrong with the configuration...