Advanced File Field now working on WP engine

I'm trying to use the Advanced File upload field on a form on this page:
http://quapawcasino.wpengine.com/job-application/

I'm seeing this error in the console:

(index):102 Uncaught TypeError: Cannot set property 'value' of null
at window.onload ((index):102)
/wp-admin/admin-ajax.php:1 Failed to load resource: the server responded with a status of 400 (Bad Request)
(index):1 Access to XMLHttpRequest at 'https://quapawcasino.wpengine.com/wp-admin/async-upload.php' (redirected from 'http://quapawcasino.wpengine.com/wp-admin/async-upload.php') from origin 'http://quapawcasino.wpengine.com' has been blocked by CORS policy: Response to preflight request doesn't pass access control check: Redirect is not allowed for a preflight request.
/wp-admin/async-upload.php:1 Failed to load resource: net::ERR_FAILED
/wp-admin/admin-ajax.php:1 Failed to load resource: the server responded with a status of 400 (Bad Request)

I contacted wp engine support with this error. They said:
A request beginning in ' would result in a bad request on our platform.
Look like its trying to request 'https://quapawcasino.wpengine.com/wp-admin/async-upload.php'