When selecting Subscriber Address for the List to Address field - if you have a more than X amount of subscribers, it is sending the List Address (even though Subscriber Address is selected).  I've tested it with a small amount of users and it works fine.  However once you load over X - it seems to default to using the list address for some reason.  I'm not sure what the X value is but it seemed to have worked fine with 377 but when sent with 495 and 656 it used the wrong To address.