You are doing this on an acf/save_post hook. That means that this happens after the post is created and this will always be true. So, none of your code is being run.
if($post_id != 'new') {
return $post_id;
}
Completely missed that this was with acf_form() and that part of your code.
It does not even matter that this does not match the post_id setting for acf_form().
You will need to find another way to test, maybe a combination of is_admin() and get_post_type($post_id)
if (is_admin() || get_post_type($post_id) != 'post_type_listings') {
return;
}
