FOX - Currency Switcher Professional for WooCommerce

Plugin link: https://wordpress.org/plugins/printful-shipping-for-woocommerce/

• In file wp-content\plugins\printful-shipping-for-woocommerce\includes\class-printful-shipping.php add next code:

  if (class_exists('WOOCS')) {
      global $WOOCS;
      $request['currency'] = $WOOCS->default_currency;
  }