Version 8.6.6
I guess it’s the pro version after looking at your website, as it appears to have pro features enabled. I had this site dev’d for me.
So I just paid for the pro version, did the update myself, and it seems to be resolved with the latest version.
Also noticed on when submitting the form with console open, I’m getting a 500 error for /wp-admin/admin-ajax.php.
I’ve checked the file exists and permissions are set. I don’t have .htaccess, and ngix isn’t blocking it.