Not much of a mystery here! The cause is straightforward.
Checking your F12 Console, you'll see this error:
That's because you're trying to use the global MktoForms2 object before it exists. And the reason it doesn't exist is you've added the defer attribute to the script tag (it's not there by default):
<script src="//go.datadimensions.com/js/forms2/js/forms2.min.js" defer></script>
defer — by design — does not load the script immediately, instead deferring it to a background fetch.
This means in the very next inline <script>, when you try to run MktoForms2.loadForm, it fails. This is expected behavior.
While defer means loading an external JS file won't block rendering of your page, it also means you need your code to be aware that you're defer-ing. You can't just add in that attribute without potentially upsetting things.
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