https://github.com/postmanlabs/postman-app-support/issues/191 Following that thread here seems that setting the request header to Content-Type multipart/form-data I'm overriding the value set by Postman.
There is no need to add a content-type header manually. You are overriding the value set by Postman. Just select form-data in POST request and send your request to see if it works.
Removing the header allowed me to hit my endpoint.