Can't get AWS SNS to work with Workflows

Has anyone had any luck creating an AWS SNS topic and sending notifications to Workflows? In AWS, I've created a HTTPS subscription for a SNS topic and used my Workflow's webhook URL as the endpoint.

Apparently AWS sends a POST request to the endpoint with headers and a JSON body that needs to be parsed. The POST request is hitting the workflow but I'm not seeing any data coming through, startTrigger.data and startTrigger.headers are undefined and startTrigger.metadata is empty.