Install Intercom using Google Tag Manager

intercom.html

<script>
  window.intercomSettings = {
    app_id: 'APP_ID',
    name: "Jane Doe", // Full name
    email: "customer@example.com", // Email address
    created_at: 1312182000 // Signup date as a Unix timestamp
  };
</script>
<script>
(function() {
  var w = window;
  var ic = w.Intercom;
  if (typeof ic === "function") {
    ic('reattach_activator');
    ic('update', intercomSettings);
  } else {
    var d = document;
    var i = function() {
      i.c(arguments)
    };
    i.q = [];
    i.c = function(args) {
      i.q.push(args)
    };
    w.Intercom = i;

    var s = d.createElement('script');
    s.type = 'text/javascript';
    s.async = true;
    s.src = 'https://widget.intercom.io/widget/APP_ID';
    var x = d.getElementsByTagName('script')[0];
    x.parentNode.insertBefore(s, x);
  }
})()
</script>

In case someone else is having similar trouble as us, I'm posting the modified version of the Intercom tag that works with Google Tag Manager.

The original version binds to the window's load event in order to load the Intercom widget. The event is typically dispatched before GTM places the Intercom tag therefore the widget never loads.

The modified version will load the Intercom widget immediately.