When creating a ship request with the carrier set to a rate group, when the ship request is loaded into the Mailcenter App, the system automatically displays the rate shop screen.
This is expected behavior.
If you need to change the shipment, close the rate shop section by selecting the X in the upper right corner. This allows you to access the Mailcenter App to modify the shipment details. When finished, click the Rate button to reprocess the rate shop.
UPDATED: February 12, 2020