Some relationships are uni-directional, meaning they appear on one entity but not the other.

Here's a good example:
https://beta.bookbrainz.org/edition-group/57806e09-3b98-4fb5-93f5-7875e4abbf23

has no relationships, but the following authors have a relationship to it (I might add a relationship that shouldn't exist between an Author and an EditionGroup back from the day where this was possible):

https://beta.bookbrainz.org/author/33607c52-2759-43ea-bd72-d4bae7b083fd
[https://beta.bookbrainz.org/author/a4d57e23-dde6-4f52-9d04-386da764b8a0

]

Two possible solution:

1. delete the offending relationships (maybe as part of a cleanup script/operation that targets relationships where source type and target type do not match the expected relationship types)
2. add the relationship to the side that is missing it