Hey Gang,
Please - can someone help. I have been using this successfully on 2 different ZenCart sites for months ... and now, for the last 30+ days or so, nothing is working.

The error in the Integration Console Error Logs at SellerCentral is usually:
Either there was a problem connecting to your endpoint or the merchant endpoint returned an invalid response status code.

When I checkout the /checkoutbyamazon/logs/ on my server, there is nothing there, so no error logs or anything on the server.
We're getting email notices that an order happened, but the orders are not posting back into ZenCart:

We are also getting tons of errors with this message:
The OrderCalculationsResponse could not be validated. Details: The XML could not be validated against the schema [cvc-complex-type.2.4.b: The content of element 'ShippingMethod' is not complete. One of '{"http://payments.amazon.com/checkout/2009-05-15/":ShippingMethodId}' is expected.].



I am a loss, we haven't changed anything?? I hope someone can offer some insights?