Those 30/60/90 days fields are calculated on the fly when printing statements. If a transaction has a due date that makes it overdue by 1-30 days, then it's current balance will appear in that aging total.

Perhaps preview the Statement for that customer, using a print date in September - Adagio recalculates all the transactions and aging categories based on the print date. Also check the due dates for the outstanding transactions for that customer.

Lastly, note that there are 2 different sets of aging fields on statements - one is based on Due date, and the other based on Document date. I assume the desired fields have been used for your statement form?