No response in a test, no helpful information for debugging
I just set up a staging server for running tests, and I switched one of my echo's over to it. When I try to run a test I get "The remote endpoint could not be called, or the response it returned was invalid." back, but there is no log of Amazon trying to connect to my server, and when I copy the request into Postman it works perfectly! It would be nice to know what the exact failure was: 404, hostname not found, invalid certificate, etc.