It took me a long time to find out why I couldn't move my cards from the backlog to the kanban board. Then I realize that my cards were imported from a excel file, with the 'current owner' field blank, and I was using smart lanes based on the team member. In this case, swift-kanban doesn't recognize that blank is the of 'unsassigned' so the cards just can't be moved from the backlog. After I fill all the fields with the string 'unassigned' the problem was solved.