I’ve had similar problem, maybe it’s not js issue, but XML instead.
Check if there are white spaces at end of the files involved ( after the PHP closing tag “?>”)
Hope it helps!
UPDATE
maybe ajax cross domain issue ( 307 Temporary Redirect ) last chance:
Set this entries on your .htaccess file
SetEnvIf Origin "^http(s)?://(.+\.)?(abc\.com)$" origin_is=$0
Header always set Access-Control-Allow-Origin %{origin_is}e env=origin_is
replace abc\.com with your actual domain. For eg: (google\.com)