ASP.NET 5/Core/vNext CORS not working even if allowing pretty much everything

Question

I have a ASP.NET 5 Web API (Well, MVC now anyway) back-end which I am consuming in with the axios library in my JS app.

My CORS config in MVC is the following:

Answer 1

The problem was actually in the fact that there was an exception in the action processing the POST request and as Norgerman mentioned, the default exception handler cleared the CORS headers.