The shipping labels option disappears when I select the USPS Global Express Guaranteed option. It calculates the shipping cost correctly, just don't have the option to print labels.
According to the Endicia documentation, Global Express Guaranteed is not a supported method for label creation. The international USPS methods supported for label creation by Endicia are: First Class Mail International, USPS Priority Mail Express International, and USPS Priority Mail International. You are still able to enter the shipment's tracking code(s)for the line items at the order level and mark as Shipped so the customer will be notified and can track the package.