B2C: Can't sign out from Edge

I'm using Azure AD B2C to authenticate users for a .Net web app.  Sign up/sign in works great.  When a user signs out, there's no problem from IE11 or Chrome.  Edge, ironically, tries to sign the user out but on redirect back to the sign in page, it's being bypassed and the user gets right back into the app.  

For reference, here's the code, it's the exact code that came from the B2C sample web project:

        public void SignOut()
        {
            // To sign out the user, you should issue an OpenIDConnect sign out request.
            if (Request.IsAuthenticated)
            {
                IEnumerable<AuthenticationDescription> authTypes = HttpContext.GetOwinContext().Authentication.GetAuthenticationTypes();
                HttpContext.GetOwinContext().Authentication.SignOut(authTypes.Select(t => t.AuthenticationType).ToArray());
                Request.GetOwinContext().Authentication.GetAuthenticationTypes();
            }
        }