When I have an album with a main artist + guest artist or 2 main artists that I have tagged with MusicBrainz artist Id's
I have set up the custom web link editor to remove the extra Id's and leave only the first one for the link:
$IsNull(<M.Brainz Artist Id>,,$If($Contains(<M.Brainz Artist Id>,";")="T",https://musicbrainz.org/artist/$Split(<M.Brainz Artist Id>,";",1),https://musicbrainz.org/artist/<M.Brainz Artist Id>))
This works fine when I select "Preview" but when I click the generated link in track info panel, the info has not been split:
https://musicbrainz.org/artist/6b064ead-91a4-4ac8-8076-b1febe4f4aac; bd53f9a7-8be9-46b0-bf7d-1deea3cb57bc