Is that code inside the product form.
Is form=“product_form_{{product.id }}” outputing the actual ID that matches the target product form. Not every theme uses the same conventions. You will have to inspect the webpage source code and find elements to confirm.
If you need this fixed then contact me directly by mail for services.
Please always provide context, examples: store url, theme name, post url(s) , or any further detail.
Contact Info in signature.
Good Hunting.