Netting off Unallocated Receipts against Unallocated Payments?

I posted this 6 months ago and got an answer from John: Hi Paul, Ah this is a case of refunding an overpayment - hopefully the guide below should explain the whole process, if you get stuck or have any queries just let me know. https://www.clearbooks.co.uk/support/guides/money-2/mangemoney/refunding-an-overpayment/

HOWEVER I did the above and it cleared off the balances.
To check all is good if I look at the customer's statement it shows all clear and nothing owing. BUT.... If I run an Aged Debtors Report the amount is still showing in the 61+ days column (even though the customer's statement says it isn't owing.

Is this a flaw in the system or have I done something wrong?
If someone from Clearbooks support reads this and wants to check in my system the following are the relevant details: Transactions 2076, 2077 Purchase 575 Invoice 356