Thanks Cédric,
The problem was that the command
_paq.push(["addEcommerceItem",product.id, product.name, product.category, product.price, product.quantity])
wouldn’t work with a SKU that is a number (please see the documentation here). It needs to be stringified. You can either make sure that it’s pushed as a string or use toString() method to convert the product.id to a string. Once the product.id is stringified, everything works:
Please let me know if it helped.