Credit memo is not showing Original Transaction number

Summary:

Content (please ensure you mask any confidential information):

We created a Sales Order and then processed a Return Order against it. After running the AutoInvoice program, the system generated both the Invoice and the Credit Memo successfully. However, the Credit Memo did not have the Original Transaction Number populated.
Is this the standard functionality in Oracle Receivables? Our expectation is that the Credit Memo should reference the original Invoice when both are created in the same AutoInvoice run. We do not want to run separate AutoInvoice processes for Invoices and Credit Memos.
Please advise:

Why is the Original Transaction Number not stamped in this scenario?