Why is there an after cursor, although the set has no data?

I have the following simplified collection with the computed field invitations.

collection Organization {
    name: String

    compute invitations: Set<Invitation> | Null = (org => Invitation.all().where(.organization == org))
}

invitations can be Null or should return

data: Array<Invitation>
after: String?

But if I run an example query Organization.byId("123456"), that should return null for the computed field invitations, it returns interestingly an after cursor, but no data:

Dashboard:

{
  id: "123456",
  coll: Organization,
  name: "TestCompany",
  invitations: "hdWC1YLGakludml0YXRpb26ByoRjYWxsgPT2gcqEZiR3aGVyZYLUgsaDY29yZ/bGYnYwx8yDgWUkdGhpc/bOg9WCxmUkdGhpc4HJgmxvcmdhbml6YXRpb270Yj09xmNvcmfGYnYx9PaCzUoF4iaVyyAA0AQF9vbBghpnxrZ6GjsCM4AQ",
}

If I do the same via the fauna js client it looks like this:
image

As the field data is mandatory and the after cursor can be null/undefined + the fact that the computed value is not returning any documents from Invitations (As the collection is empty) I’m quite surprised that there is an after cursor after all.