[whpalmer4]

It is the intended behavior, and a rationale for doing it this way is that it prevents unpleasant surprises where an item has a start date just before the due date. One way of thinking about it is that it doesn't show Available actions filtered by those which are Due Soon, it shows Remaining actions filtered by those which are Due Soon. Similarly, the Available actions filter shows Remaining actions filtered by those which are Available, and Next Actions shows Remaining actions filtered by those which are Next Actions.