Credit Memo is not getting created for a service contract

There is service contract which got created based on a sales order . "Service Billing Option" is ‘First Period Billing from OM, Subsequent from Contracts’ and Service Billing Profile is 'Immediate' on the service items of the sales order line. Contract got created with 'Bill Services' as 'Yes'. Invoice for the full amount got created based on Sales Order. Later, RMA has been created for this sales order and the service lines got terminated on the contract. We are able to see data in oks_bill_cont_lines with bill_action = 'TR' , Interface Date is also not a future date, but still