Payment does not Display on Issue Customer Refund

 
1. Go to the Payment
2. Click on Edit
3. On the Apply tab > unmark the checkbox on the Invoice
4. Save.
5. The payment should now appear on Transactions > Customers > Issue Customer Refund page to be refunded.

Note: Customers usually refund overpayments. These overpayments are recorded in Netsuite as 'Unapplied Payment', or payments that are not applied to any invoices. Such payments are showing on Issue Customer Refund screen > Apply tab > Credits subtab.
However, there are also instances when a customer wants to refund incorrectly entered and applied payments on invoices. Such payments, which are 'Applied Payments', do not normally show on Issue Customer Refund screen > Apply tab > Credits subtab.