A payment was placed into an open accounting period of April, while the service detail this payment is for was placed into May.
The report is generated as of 04/30 so the payment or adjustment is included in it but the service line does not exist on 04/30 based on accounting dates .
Basically,the transactions is included in the report - but we don't know where to place it because based on the report's logic we have no idea which row or column this transaction would belong to.
Non-aged transactions may appear when certain transactions have earlier accounting date than the charge transaction of the service line they are posted against