ASP.NET Web API & REACT - CORS Issue in ASP.NET Identity Login

Question

Hello I'm having an Issue with ASP.NET WEB API Login. I've already enabled CORS in my back end

here is from my WebApiConfig.cs

var cors = new EnableCorsAttribute(origins: "*", headers: "*", methods: "*");
            config.EnableCors(cors);

web.config

 <customHeaders>
   <add name="Access-Control-Allow-Origin" value="*" />
   <add name="Access-Control-Allow-Headers" value="Origin, X-Requested-With, Content-Type, Accept,Authorization" />
   <add name="Access-Control-Allow-Methods" value="GET, POST, PUT, DELETE, OPTIONS" />
  </customHeaders>

from my REACT APP

 var params = {
                'userName' : this.state.email,
                'password' : this.state.password,
                'grant_type' : 'password'
            };

            var formData = new FormData();

            for (var k in params) {
                formData.append(k, params[k]);
            }

            fetch(loginApiUrl, {
                method: 'post',
                headers : {
                    'Access-Control-Allow-Origin' : '*',
                    'Accept' : 'application/json',
                    'Content-Type': 'application/x-www-form-urlencoded',
                },
                body : formData
            })
            .then(json => json())
            .then(x => {
                alert(json.access_token)
               // localStorage.setItem('auth_token', `Bearer ${json.access_token}`)
            })

And I also use webpack dev server here is the config to allow CORS

 devServer : {
        headers: { "Access-Control-Allow-Origin": "*" },
        contentBase : path.join(__dirname, "dist"),
        compress : true,
        hot: true,
        open: true,
    },

And I keep getting this error from Google chrome console

Failed to load http://localhost:xxxx/token: Response for preflight does not have HTTP ok status.

Any help to get this to use OPTIONS verb?