APEX_WEB_SERVICE.make_rest_request REST API sometimes returns a null response

Summary:

During Project Cost Split/Transfer operations, the APEX_WEB_SERVICE.make_rest_request REST API sometimes returns a null response. Is this expected behaviour?

Kindly refer to the sample payload provided below.

Sample Payload:

{"name":"adjustProjectCosts",
"parameters":[
{"AdjustmentType": "Split"},
{"Quantity": "1"}
]
}

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