https://musicbrainz.org/artist/3de86034-6825-4053-b67a-94bd0f383026/relationships has a member relationship, but also a conductor relationship. It is still shown under PossibleCollaborations.

If I'm reading the report query correctly, it currently checks each relationship separately, and makes sure it's a member / collaborator one. As such, even if an artist has the right relationship, it will still be listed if it has at least one artist-artist relationship that is not member or collaborator.