|Shipping Type Options|
|Address Information Maintenance|
So, if you find the Ship to Address is missing from a Purchase Order, start by checking the Shipping Method, as it's the likely cause. If the purchase order has a Shipping Method assigned, then you may have an Address ID which has no address information. Use the chart above as a reference to determine where the Purchase Order Address should be originate from.
Finally, if Dynamics GP isn't behaving as it should, it is entirely possible a customization is at fault.
I hope this helps get you where you're going.