Invalid token when trying to get a User

I am not sure what I am doing wrong here.
I have set up a local application and a local API which has machine-to-machine access to the Auth0 Management API.
All of this works fine locally.

So, I set up a new application and API and then published to my development slots. I can login fine, but when my API tries to get the current User it fails with an “invalid token” error. As far as I can tell I am doing everything right. The API has machine-to-machine access to the Auth0 Mangement API. I am using the right ClientId and Secret (for the API [Test Application]) and the correct audience is set up.

Does anyone know what I am doing wrong?