Hi, We recently applied for the Web Merchant Registration API and created our platform integrator ID. I am trying to register a domain in sandbox with the API: POST https://apple-pay-gateway-cert.apple.com/paymentservices/registerMerchant Content-Type: application/json { "domainNames": ["<URL>"], "partnerInternalMerchantIdentifier": "<merchant_id>", "partnerMerchantName": "<merchant_name>", "encryptTo": "<platform_integrator_id>" } Client certificate is provided via curl --cert/--key; the TLS 1.3 handshake completes successfully — the server requests the client cert, our Certificate + CERT verify are accepted, and the connection is established. But the response is { "statusMessage": "Payment Services Exception Unauthorized", "statusCode": "401" } How do I go about debugging this?