I have 27 digital only products in my store; somehow one of them is published with Klaviyo, but none of the others are. It has taken me a while to reach this point in my integration with Shopify to discover why my Kalviyo emails are picking up only the one digital product. I am on the free plan. I first installed Klaviyo when I created my Shopify store, so my 60 days of being able to contact support to ask for the backend to be corrected is long gone.

I found this in a previous post:

With that said, there is a setting we (Klaviyo) can enable on the backend of your Klaviyo account to ignore the inventory quantity. Enabling this setting will allow your products to populate in the feed regardless of their stock/inventory quantity. Since this is an “ignore” setting, the caveat here is that it will display all items in the feed even if they are legitimately out of stock. 

If you would like this feature enabled, please file a request with our support team and they will be happy to take care of this for you.