This was the form action code written by the new DA version that was released.
Unfortunately the form does not submit any data.
It is a plugin using frame builder in a page called index.php?survey=dual_membership
When a form is submitted, no data is sent, and you are directed back to the same page minus the dynamic url instead of ../thankyou.php, the form action is actually /admin/survey/index.php
If I set the form action to /admin/survey/index.php?survey=dual_membership the data sends with no problem and the redirect works as expected.