i did this with a dynamic selection
My client is in dutch so it could be that your field and table names differ a little bit
i start with the selection on the table "tickets"
the one who sends the ticket is person, and this person relates to a company
therefore i use the field person/company
just click the + sign before person to unfold the list
as you can see i chose as criteria for persoon/bedrijf "isempty"
so you get al cases of contacts who are not related to companies
please note -> im in advanced view which can be chosen in the hamburger menu when selecting criteria
otherwise the "is empty" option will not be available
This is the way i implemented this in our company, i hope it suits you