IMS is not updated in real time to reflect actual stock in the store, which is absolutely insane to me. Changes in current orders are not emailed to the customer in a timely manner, takes about 24 hours for the automated system to send the email which at that point you've already gone out of your way to figure out what's going on with your order.
Stay away from Target's online ordering if you value your time. It will be wasted, guaranteed.