Comment 2 for bug 439948

Now that you mention it, this behavior makes perfect sense. My problem was caused by the initial rank being equal to the ticket id. I already had milestones called "Backlog" and "SprintX". Both milestones had tickets assigned to them before installing the plugin. When I moved tickets from Backlog to SprintX and back, the ordering was not what I expected, since the tickets already in SprintX were not originally ordered in relation to the tickets in Backlog.

It all makes sense now, but perhaps it should be noted somewhere that you really need to start with an empty sprint milestone?