Update: This change will be completed at noon EST on Friday April 13, 2012
In the Transactions API, a bug has been discovered where the `product_id` being returned is not actually representative of the product the subscription was subscribed to at the time of the transaction. Instead, the *current* product for the subscription is being returned. This is only a problem if the subscription has gone through a product change - in this case, the product change would not be reflected in the `product_id` of the account transactions. All account transactions would show the same product id.
All new account transactions records going forward will return the `product_id` of the product the subscription was subscribed to at the time the transaction occurred. Consequently, older account transactions may return a nil `product_id` field when we release this fix, signifying that we are unsure which product the subscription was subscribed to at the time the transaction occurred. We will be backfilling as much data here as possible, so we hope that getting a nil result for the `product_id` field is more the exception than the rule.
This change will be deployed in an upcoming release, so stay tuned.
You should be sure that your integration code can handle a nil value for the `product_id` field for the account transactions endpoint