Why does the customer pay 0 freight, but the estimated freight has a cost value?

Hello, if the above situation occurs, please check:

1) Does the customer go through the service group where the warehouse configuration freight is 0? (This service is generally the billing method of bill third-party account);

2) Please check the default rate settings from the top right corner Settings ->Shipping Service Settings ->Service Setting ->Manage Shipping Service ->default rate setting,whether to configure the customer to pay freight as 0;

3) Please confirm whether the order status is not cancelled. If it is cancelled, the freight paid by the OMS customer must be 0.