This is currently an enhancement in NetSuite under Issue #228396 - Payment Processing: Transactions > Sales > Bill Sales Order > Save the payment event details whenever the settlement/capture request failed and no cash sale is generated.
Check the Transaction Audit Log, transaction numbering audit log that provides a complete list of every transaction number, including the numbers that were assigned to transactions that have been deleted or failed to be created (for example, Cash Sales that failed due to problems with credit card processing).
Below are the detailed steps:
1. Navigate to Transactions > Management > Transaction Numbering Audit Log.
2. On for footer of the report under column : 'Transaction Type' choose Cash Sale.
3. Look for the Cash Sale Transaction and check previously created transaction numbers. These numbers are generated when you tried to create Cash Sale transaction but they were not recorded as the credit card transactions failed.