Steps to reproduce:
Order application, Order Entry.
Internal Org: Company...
User Login: admin
Supplier: Big Supplier
Click Continue, and click continue again
In the second part of the Create Purchase Order Screen, enter
Item Type: Bulk Item
Click Add To Order.
Click Finalize Order.
On Ship Group Nbr 1 screen:
In the Ship to Another Party section, add Party Id of "AcctBigSupplier".
Click Continue. Entered Party ID silently discarded with no feedback why the entered Party ID wasn't valid.