When creating INBOUND shipment I get 504 (gateway time-out) or 204 (No Content) instead of 201 (Created)

I use shipment v2 API in playground.


JSON data of my request:

{
    "type": "INBOUND",
    "requestedDateTime": "2023-03-02T10:45:41Z",
    "cageId": "1234",
    "details": {
        "carrier": "OTHER",
        "carrierName": "New Carrier",
        "numberOfBoxes": 2,
        "carrierTrackingNumbers": [
            "t1Z294AK92654678989",
            "t1Z086DK96424456780"
        ]
    }
}

I get two possible responses for this same request:

504 gateway time-out error

{
    "fault": {
        "faultstring": "Gateway Timeout",
        "detail": {
            "errorcode": "messaging.adaptors.http.flow.GatewayTimeout"
        }
    }
}

204 No Content

However according to API docs, I should get 201 and the order id.