I've created a GitHub issue (
https://github.com/lat9/one_page_checkout/issues/203) to track the changes for this unwanted behavior, which affects all payment methods that 'collect credit cart information on-site'.
The jist is that for this processing, the call to the
zcAjaxPayment processing to initiate that confirmation sends back some jQuery to be run at document ready. The OPC AJAX was being too quick with its form-submission so that the payment-method processing wasn't being run.
The correction is to (a) ensure that the payment methods' jQuery runs on the
ajaxComplete event and (b) stage OPC's form-submittal to the
end of the
ajaxComplete event.