I also have the same problem. From my understanding from here https://help.shopify.com/en/manual/orders/status-tracking/customize-order-status/add-conversion-tracking we can pass any value in the product ref param (e.g. https://[shop-name].myshopify.com/products/[product-name]?ref=[unique-ID]) and it’ll be forwarded to webhooks (I’m listening to orders/paid to be precise). However, what I get in landing_site_ref is always null.