Cannot hit HTTP API endpoint from Xero

I have made a Lambda function and an HTTP API. I am able to hit the API and trigger the Lambda function from Postman. However, when I send the Xero "Intent to receive" it does not even seem to be hitting the API endpoint as it is not generating a log. The Xero "Intent to receive" is received when I point it to ngrok or another service, but for some reason does not seem to be able to hit the AWS API that I have created. I have added * and https://xero.com to the API CORS Access-Control-Allow-Origin. I have checked Security Groups and there don't seem to be any rules that would block the Xero requests from coming through. I don't really know what else to try. The Xero docs relating to AWS are out of date.