FOX - WooCommerce Currency Switcher Professional

Plugin URL: https://wordpress.org/plugins/woocommerce-delivery-notes/

Into file functions.php of the current wp theme add next code:

add_action('wcdn_after_info', function ($order) {
    if ($order AND class_exists('WOOCS')) {
        global $WOOCS;
        $currency = $order->get_currency();
        if (!empty($currency)) {
            $WOOCS->current_currency = $currency;
        }
    }
});