The public user has access to the primary document being searched but does not have permission to view a linked document (Document Relationships).  This does not allow the primary document to be viewed and produces an error message:

Is this by design as you may not want users to see the title of a linked document?  If they give permissions to the linked document, it works as expected, however the users are able to view the linked document and this is not the desired result.

Weblink v9.0.1350

LFS v10.4.1.193