The store order summary server behavior on this page is triggered on the posted Checkout element. Are you posting to this page from a different checkout page first? If not this will not work because the Checkout element is the submit button on this page and the form's action is set to the confirm page. You should have this store order summary server behavior on the confirm page that this page posts to.
If you want to make it so the store order summary only occurs after the transaction you should use the same trigger as the local checkout server behavior like this:
php:
if (($_SERVER["REQUEST_METHOD"] == "POST") && (isset($_SERVER["HTTP_REFERER"]) && strpos(urldecode($_SERVER["HTTP_REFERER"]), urldecode($_SERVER["SERVER_NAME"].$_SERVER["PHP_SELF"])) > 0) && isset($_POST)) {
If your checkout server behavior is being triggered then this should be as well after making this update.
