I just made a change to our Kanban Board's swimlane settings (Kanban Board → Configure board → Swimlanes) such that the "Select method" is set to "Assignee" and the option to show unassigned issues is set to "Show above other swimlanes". This all worked fine, my having been to simply to show the unassigned above other swimlanes. All good at this point.
I was then curious about the "Group By" filter menu shown at the top of the board. I noted that it was set to "None" and then changed it to "Assignee". Doing so moved the "Unassigned" swimlane below the other swimlanes, reversing what I had set in the board's swimlane settings. Re-visiting the Kanban Board → Configure board → Swimlanes settings confirms that it's still set to "Show above other swimlanes". And, now, if I change the Group By filter on the board back to "None", the swimlanes disappear completely (which is at odds with the initial setting of "None" that I mentioned above).
Now I'm back to where I started and can't seem to do anything about it: the Unassigned swimlane appears below the others.
Any suggestions?