OTM Export API is not returning json response

i am getting a 400 error, Content error in message body. When i change the content Type to  "application/json"

API: logisticsRestApi/data-int/v1/exportRequests

Request:

{    "schema": "PRIMARY",    "contentType": "application/json",    "rangeAfter" : {        "value": "2025-01-01T00:00:00Z"    },    "rangeBefore": {        "value": "2025-07-01T23:59:59Z"    },    "tables" : {        "items" : [            {                "tableName": "SHIPMENT",                "selectList": "SHIPMENT_GID,SHIPMENT_NAME,PERSPECTIVE,INSERT_DATE,UPDATE_DATE"            }        ]    }}

Response:

{    "status": 400,    "title": "Content error in message body.",    "detail": "Unknown error."}