in the WA_Universal_Email/Email_Templates/contactus.php file, change:
if ($pval != "" && strpos($pkey,"Security_") !== 0 && $pkey != "x" && $pkey != "y") {
to:
if ($pval != "" && strpos($pkey,"Security_") !== 0 && $pkey != "x" && $pkey != "y" && $pkey != "Submit") {