attachment post type

Looks like Group listing is duplicated on Attachments, so you need to uncheck box in both lists.

Try this in functions.php (it removes extra meta box on Attachments page)

add_action('admin_menu', 'remove_uma_metabox');

function remove_uma_metabox() {
        remove_meta_box( 'uma_post_access', 'attachment', 'side' );
}