Unable to Withdraw a Tender

We are using OTM v5.5.3.6 on a 64 bit Windows environment.

We have a buy shipment that has two orders on it. The shipment has indicator colour GREEN and status SECURE RESOURCES value SECURE RESOURCES_ACCEPTED.

Unfortunately, only one of the orders on the shipment was picked up and delivered. We are now trying to UNASSIGN the order that was not picked up so that we can create another shipment for it. Before we can do this, we need to WITHDRAW the tender from this shipment but it is not allowing us to do this and giving us the error:

"Cannot withdraw tender for shipment 064796, please check if the shipment has been previously withdrawn or declined." We checked this and the tender has not already been withdrawn or declined. The only change to the status was when the carrier accepted the tender. Can someone give me some suggestions as to why I cannot make this change? We have had this happen in the past and were able to withdraw a tender and unassign the order. Thanks.