Seem to only find this button (see PNG) on the page in drupal/cart/checkout field and not a listing of products purchased. Using Uber 1.6. However, the cart is setup so that no pricing is displayed. The customer receives an invoice and the firm receives a copy of that information. i.e. customer and admin templates in uc_order/templates. Nothing more.....
Thus shipping, shipping quotes, fulfillment and payment modules have not been installed. Perhaps without these additional modules not being installed is causing the issue.
However, just the addition of the button to add an existing address is a huge plus. Something that all carts should have.