Web chat embedding problem

Hi

I am trying to implement the web chat embedding into a frame as per the new video from Voiceflow. Whilst I can get the overlay method working I am having problems with getting the frame method working. Here is my code:
<div class="iframe-container">
<iframe id="voiceflow-frame" width="800" height="500" frameborder="0"></iframe>
<div id="blank-state" style="display: flex;"></div>

</div>

<script type="text/javascript">
(function(d, t) {
var v = d.createElement(t), s = d.getElementsByTagName(t)[0];
v.onload = function() {
window.voiceflow.chat.load({
verify: { projectID: '65e070d88c2b8b812acd3a02' },
url: 'https://general-runtime.voiceflow.com',
versionID: 'production',
render: {
mode: 'embedded',
target: document.getElementById('voiceflow-frame'),
},
autostart: true
});
}
v.src = "https://cdn.voiceflow.com/widget/bundle.mjs"; v.type = "text/javascript"; s.parentNode.insertBefore(v, s);
})(document, 'script');
</script>

Can anyone help me out?

Thanks
steve