question

I'm recently trying to integrate Login With Amazon (LWA) with my website by following this instruction. However, when retrieving token by calling amazon.Login.retrieveToken(), I kept getting error as:

"oauth error (retrieveToken) UnsupportedOperation: Cookie amazon_Login_pkce_params not found. Cannot retrieve token without cookie."

Here is the code. I didn't find anything wrong, especially I do add "options.pkce = true;". Anyone please help me find what I missed? Thanks!

<div id="amazon-root"></div>
  <script type="text/javascript">
    window.onAmazonLoginReady = function() {
      amazon.Login.setClientId('amzn1.application-oa2-client.<Hide My Client Id Here>');
    };
    (function(d) {
      var a = d.createElement('script'); a.type = 'text/javascript';
      a.async = true; a.id = 'amazon-login-sdk';
      a.src = 'https://assets.loginwithamazon.com/sdk/na/login1.js';
      d.getElementById('amazon-root').appendChild(a);
    })(document);
  </script>
  
<a href id="LoginWithAmazon">
  <img border="0" alt="Login with Amazon"
    src="https://images-na.ssl-images-amazon.com/images/G/01/lwa/btnLWA_gold_156x32.png"
    width="156" height="32" />
</a>

<script type="text/javascript">
  document.getElementById('LoginWithAmazon').onclick = function() {
    setTimeout(window.doLogin, 1);
    return false;
  };

  window.doLogin = function() {
    options = {}
    options.scope = 'profile';
    options.pkce = true;

    amazon.Login.authorize(options, function(response) {
      if ( response.error ) {
        alert('oauth error (authorize) ' + response.error);
        return;
      }

      amazon.Login.retrieveToken(response.code, function(response) {
        if ( response.error ) {
          alert('oauth error (retrieveToken) ' + response.error);
          return;
        }
        alert('Access Token: ' + response.access_token);
      });
    });
  };
</script>