If it helps, I get this error message on my error log on the server:
id was called incorrectly. Product properties should not be accessed directly. Backtrace: require(‘wp-blog-header.php’), require_once(‘wp-includes/template-loader.php’), do_action(‘template_redirect’), WP_Hook->do_action, WP_Hook->apply_filters, WC_AJAX::do_wc_ajax, do_action(‘wc_ajax_add_to_cart’), WP_Hook->do_action, WP_Hook->apply_filters, WC_AJAX::add_to_cart, apply_filters(‘woocommerce_add_to_cart_validation’), WP_Hook->apply_filters, IPQ_Quantity_Validations->add_to_cart_validation, IPQ_Quantity_Validations->validate_single_product, wpbo_get_value_from_rule, WC_Abstract_Legacy_Product->__get, wc_doing_it_wrong. This message was added in version 3.0.