Here is the incorrect answer I received from Shopify regarding this issue. The products in question have been entered into my system for years and there has never been an issue with “cost not recorded” when I run the Finance Summary report at the end of each month. Their customer service is absolutely terrible.
After a detailed review with our technical team, we found that the orders in question were processed using custom products—in other words, products created directly through a third-party app or sales channel (such as Facebook, Instagram, or subscription-based apps), rather than from your existing product catalog. When this happens, Shopify is unable to associate the cost that was originally recorded for the product, since the item is treated as new or separate at the time of the order.