Hi Scotty,
You seem to be applying the settings properly. When you go into that layout and page setup - you are selecting for this layout only right?
Let's start with the basics.
If you take a simple document and you try to duplex will it work?
If that works - try to create a multi-page document in Word and try to do MixPlexing and see if that works.
If you are able to get it to work in Word there is no reason it shouldn't work in PSM.
If you are still struggling I would recommend opening up a support call so we can assist you further.
http://printshopmail.objectiflune.com/en/resources#And click on report an issue.
Best Regards,