In my flac files, which I have imported into beets, everything is ok with the tags. But when I convert them, in my case into opus files, only one musicbrainz_albumartistid remains. Multiple IDs are essential to classical music, and Picard retrieves them from the musicbrainz server. And Kodi relies on them to be present. So, I guess it is a bug, that these additional musicbrainz_albumartistids get lost?
I'm not sure how this can happen, because I thought it only uses the command which I have specified in the config file:
command: opusenc --bitrate 160 $source $dest
But when I use this opusenc command manually, all of the tags are there...