How to insert multiple records in ATP staging table with help of ORDS Rest Service ?

Summary: We are trying to insert multiple records in ATP staging table , I got success with One Records only but when we are trying to multiple records its failing for we get the response 201 creation but in the staging table all the values are null.

Content (please ensure you mask any confidential information):

{
"items": [
{
"origin_system": "LEGACY_APP2",
"registry_id": 1002,
"original_system_reference": "CUST-REF-001",
"organization_name": "XYZ Technologies Pvt Ltd",
"relationship_type": "SUPPLIER",
"customer_account_group": "RETAIL",
"account_unique_id": 50002,
"account_number": "ACC1003",
"account_description": "Main Retail Customer Account",
"account_type": "STANDARD",
"account_established_date": "2020-05-15T00:00:00Z",
"customer_class": "CORPORATE",