Update nav menu not selecting parent

As I originally suspected, menu-item-parent-id takes the id of the menu item and not the id of the parent page.

So I referenced the menu item ID and passed it into the recursive function :

function buildMenu( $array, $menu_id, $parent_id = false ) {

    foreach ($array as $menu) {

        $menuItemId = wp_update_nav_menu_item(
            $menu_id,
            0,
            array(
                'menu-item-title'     => $menu[0]->post_title,
                'menu-item-object'    => 'page',
                'menu-item-object-id' => $menu[0]->ID,
                'menu-item-type'      => 'post_type',
                'menu-item-status'    => 'publish',
                'menu-item-parent-id' => $parent_id
            )
        );


        if(!empty($menu[1])) {
            buildMenu( $menu[1], $menu_id, $menuItemId );
        }

    }

}