Update Commitment details in change orders from REST API

Good day, everyone.

We are attempting to update the Commitment tab details in the change order screen using the REST API, but we are encountering problems when updating the Commitment type and Commitment nbr values from the API.

Commitment type is set to Purchase order by default, and if we assign PO transaction values to Commitment nbr. from API, it works fine because PO values are already loaded into selector.

However, when we assign "Subcontract" type to Commitment type and subcontract # to Commitment nbr via API, we receive an error stating that the subcontract was not found in the system.

The JSON and URL for this call are shown below. Can anyone suggest a solution to this problem?

PUT: {{SiteURL}}entity/DefaultEx/18.200.001/ChangeOrder

{
   "RefNbr": {
        "value": "000020"
    },
    "COMMITMENTS": [
        {
            "ACCOUNT": {
                "VALUE": "51250"
            },
            "AMOUNT": {
                "VALUE": 600432.0000
            },
            "CostCode": {
                "value": "00000"
            },
            "DESCRIPTION": {
                "VALUE": "CONSTRUCTION API 1"
            },
            "INVENTORYID": {
                "VALUE": "CSTRSUBCON"
            },
            "PROJECTTASKID": {
                "VALUE": "09"
            },
            "QTY": {
                "VALUE": 0.000000
            },
            "CommitmentType": {
                "VALUE": "Subcontract"
            },
            "PONBR": {
                "VALUE":"SC-000001"//"PO001295"
            },
            "POLINENBR": {},
            "UNITCOST": {
                "VALUE": 0.0000
            },
            "UOM": {
                "VALUE": "LS"
            },
            "VENDOR": {
                "VALUE": "SUNTECH"
            }
        }
    ]
}

 "exceptionMessage": "ChangeOrder.Commitments[0].PONbr: Commitment Nbr. 'SC-000001' cannot be found in the system.

Acumatica version: 21.217.0035

Thanks