Owin, WebApi and UseCookieAuthentication

Question

Owin, WebApi and UseCookieAuthentication

I configured OWIN in my ASP.NET MVC application using cookie validation, but when I try to access the Authoric attribute with the Authorize attribute, authorization fails and I cannot understand why. Entering the IsAuthorized method of the Authorize attribute, I see that none of the authentication properties present when accessing the MVC is present, so it certainly appears (at least with the authorize attribute) that the user is not authenticated.

The application is configured as follows:

public void ConfigureAuth(IAppBuilder app)
{
    app.CreatePerOwinContext(MyAuthContext.Create);
    app.CreatePerOwinContext<MyUserManager>(MyUserManager.Create);

    app.UseCookieAuthentication(new CookieAuthenticationOptions
    {
        AuthenticationType = DefaultAuthenticationTypes.ApplicationCookie,
        LoginPath = new PathString("/Account/Login"),
        Provider = new CookieAuthenticationProvider
        {
            OnValidateIdentity = SecurityStampValidator.OnValidateIdentity<MyUserManager, MyUser>(
                validateInterval: TimeSpan.FromMinutes(30),
                regenerateIdentity: (manager, user) => user.GenerateUserIdentityAsync(manager))
        }
    });

    app.UseExternalSignInCookie(DefaultAuthenticationTypes.ExternalCookie);

        var httpConfig = new HttpConfiguration();
        WebApiConfig.Register(httpConfig);
        app.UseWebApi(httpConfig);
}