Woocommerce programmatically added attributes to grouped product not showing on admin area

Question

I was able to add attribute value programmatically to the product and it was showing on the front but not showing in the admin area attributes.

Do I need to assign attributes to the product before adding attribute value?

add_action('woocommerce_before_product_object_save', 'nd_update_group_product_attributes_before_save_func', 1001, 2);

function nd_update_group_product_attributes_before_save_func($product, $data_store) {

     // exit if not the target post type
    if ('product' !== $post->post_type || wp_is_post_revision( $post_ID )) {
        return;
    }

    $product_type = $product->get_type();

    if ($product->is_type('grouped')) {

        $child_product_ids = $product->get_children();

        $all_child_bed_attributes = array();
        $all_child_bath_attributes = array();

        foreach ($child_product_ids as $child_product_id) {

            $child_product = wc_get_product($child_product_id);
            // $pa_bedrooms = $child_product->get_attribute('pa_bedrooms');
            $pa_bedrooms = wc_get_product_terms( $child_product_id, 'pa_bedrooms', array( 'fields' => 'names' ) );
            $pa_bathrooms = wc_get_product_terms( $child_product_id, 'pa_bathrooms', array( 'fields' => 'names' ) );
            $all_child_bed_attributes = array_unique(array_merge($all_child_bed_attributes, $pa_bedrooms));
            $all_child_bath_attributes = array_unique(array_merge($all_child_bath_attributes, $pa_bathrooms));
        }
        if ($all_child_bed_attributes) {

            foreach ($all_child_bed_attributes as $bed) {
                wp_set_object_terms($product->get_id(), $bed, 'pa_bedrooms', true);
            }
        }
        if ($all_child_bath_attributes) {

            foreach ($all_child_bath_attributes as $bath) {
                wp_set_object_terms($product->get_id(), $bath, 'pa_bathrooms', true);
            }
        }
    }


}