I was surprised to see that the endpoints that Azure Traffic Manager was monitoring were showing degraded.
I looked into it and Google said that the Traffic Manager would check for a 200 response (and it won't follow 3xx responses) from the site but from where was it calling?
I thought that the problem might be the http->https redirect I had on the site so I needed the Traffic Manager to call the https endpoint and not the http one but when you click on the endpoint and press Edit, it doesn't show the endpoint.
What you need to do INSTEAD is to click Configure on the Traffic Manager itself and set the endpoint location in there:
Note that I am using the favicon in the path. The reason for this is that if I hit the default endpoint (/) it might cause a redirect to another page. Favicon is a nice static known resource that should always return 200. You could, of course, point it to anything else.