Approved by for canceling invoice is blank

Hello Gurus,As a std oracle process, Project Invoice credits are automatically approved. But we notice that for Write-Off and Concession invoices, the approved by person is displayed as the user who has actioned the invoice credit. But for a cancelling invoice, the approved by person field is blank.
Wanted to check if this is a bug or expected functionality. If expected functionality, then wondering what could be the business logic.
Any help is appreciated.
PS: we are in R12.1.3
Regards
Andy