A requirement for USMCA is defining the Preference Criterion.
This can be found screen under each product in the product master and click on the Free Trade Info link.
On the Free Trade Info screen in Product Master, click on USMCA Preference Codes to open a new window with the codes and definitions. Place that letter in that Preference Criterion box and click save.
Please refer to Article 5.2 on this link for additional information.