In my recent order i had a back-ordered item. Oddly enough, the order status page never makes any mention that something is on back-order, it implies that everything was shipped. It seems the system isn’t “wired” to let customers know their missing piece wasn’t forgotten.
Perhaps as an feature request, it would be nice to look at my order status and see which parts were NOT fulfilled in my latest shipment. a projection of when missing items are going to ship would be pretty handy as well.