Hi Philip,
Sorry to tell you, but is not missing anything, the issue is with Hikashop and as I said this is the piece of code that is causing the issue:
<script type="text/javascript">
document.getElementById('hikashop_paypal_form').submit();
</script>
On step 1 and 2 is working fine because the above code doesn't exist, soon as you move to the PayPal page redirection this script is loaded and is breaking all templates.
I've tested on other templates like Beez and Protostar and the issues are the same and even worse on Protostar. I've attached screenshots as proof.
thanks!