bid/module/Listings/view/partials/product-attributes.phtml

<?php
/**
 * @version 7.5
 */

/* @var \Ppb\Db\Table\Row\Listing $listing */
$form = new \Listings\Form\Purchase($listing, null, 'buy');
$form->setData(
    $this->request()->getRequest()->getParams());

/** @var \Cube\Form\Element $element */
foreach ($form->getElements() as $element) {
    $name = $element->getName();

    if (strstr($name, 'product_attributes')) {
        $element->setRequired(false);
        $this->script()->addBodyCode($element->getBodyCode());
        ?>
            <div class="form-group product-attribute-element">
                <label><?php echo $element->getLabel(); ?></label>

                <?php echo $element->render(); ?>
            </div>
    <?php
    }
}