For testing perposes. This responds with 'heartbeat' when running. But when Clicking 'insert into post' or insert custom link (nav menu) among a few others the POST action never get's triggered. In my console I get 302 found, then a GET request to the home page. Example video: http://quick.as/1oovhyzj

admin.ajax.php

if ( ! empty( $_POST['action'] ) && in_array( $_POST['action'], $core_actions_post ) ) {
	die($_POST['action']);
	add_action( 'wp_ajax_' . $_POST['action'], 'wp_ajax_' . str_replace( '-', '_', $_POST['action'] ), 1 );
}