Kanban not finding collaborator field?

Hi folks. I am trying to create a Kanban view of a table that has x1 single select field and x1 collaborator field. I want to make the Kanban on the collaborator field but when I create it, it only finds the single select field and ask me if I want to create a new single select or collaborator field. Any thoughts welcome! Thanks.

Is the collaborator field an actual collaborator field, or is it a lookup of collaborators from another table?

Thanks, it is an actual collaborator field

Could you post some screenshots of what you see when you try to set this up?