We are using the kanban board for work in progress, and would like our regular backlog view to exclude cases that have any non-empty kanban state. I see that I can use a search axis filter to limit my view to one specific kanban state (e.g. "kanban: Accepted") but how can I limit the view to cases with an empty kanban state?
kanban: None (or kanban: "None") gives me an error "The requested search axis 'kanban' is not recognized."
kanban: "" gives shows cases with ANY kanban state. How do I do the opposite of that?