Let's find out why there's an open balance in the account even it's already paid, Dbartke.
There are possible reasons why the account shows an open balance in the system. It could be the payment not applied to an invoice, credit issued and not applied to an invoice, and lastly, small balances need to be written off.
To double-check if this is the scenario. Let's review the Accounts Receivable Aging Summary and the Customer Balance Detail Reports to begin to clean up open payments or credits in the account.
Once confirmed, you can apply the payment to the transaction and select the same date range.
Let me know if you need anything else. Remember, I am always here to help you. Have a great day!