You’re trying to add section editors through the “Edit Section Group > Members” tab, correct?
We’re unable to reproduce this behavior in a fresh WP 3.9.1 install. Could you provide more detail as to your setup? Browser, other active plugins, etc. Are there any Javascript errors showing up in your console?
We were able to fix the problem. It was giving the error in the console: “Uncaught ReferenceError: buse_site_users is not defined”.
This line of code below in the admin.groups.php file not loading that caused the issue:
wp_enqueue_script( ‘buse-site-users’, admin_url( ‘admin-ajax.php?action=buse_site_users_script’ ), array(), null );
So we added some codes after that to fix it:
wp_localize_script( ‘group-editor’, ‘buse_site_users’, $current_site_all_users);
That doesn’t sound right — you shouldn’t have to modify the plugin code to get it to work. 🙂
I was unable to reproduce in 3.9.1 (or any WP version for that matter) so I’m wondering if perhaps it is browser specific or maybe there is a conflict with another plugin you’re running. Was this issue limited to a specific browser / OS?