I'm trying to start using Kanban backlogs. When I have a parent task with sub tasks showing in my backlog, I'm unable to move only a single subtask to the "Todo" section (out of the backlog if you want). Once I've moved everything to "Todo", I can then move single sub-tasks in the remainder of the flow. I can drag a single sub task to "In Progress". From my reading of the documentation, I'm not getting the expected behavior, I should be able to move single sub tasks.