the issue is that the form elements are being renamed, this means you will need to edit all of the set session value behaviors on the confirm page to recognize the new form element names.
on the confirm page, go to the bindings panel. click on the plus button and select form data. click the folder icon and select the checkout page. this will add dynamic data bindings to the confirm page for the form elements from the checkout page.
you then need to go through each of the set session value behaviors on the confirm page and bind the values to the appropriate form element from the checkout page.