Outstanding deposits

I have just recently taken over some book keeping duties to help a friend out and it's been many years since I've used MYOB Account Right so I'm after some help resolve some inconsistencies I have come across with some debtor payments. The invoices have had a payment applied to them but I can't find them on any of the bank statements but they show up in the outstanding deposits section of the bank account reconciliation report for that month so where do I start looking to see if that amount has ever actually been paid because I can not find it on the bank statements anywhere but the invoice is showing as paid

some help would be appreciated I'm a little out of my depth

thank you