REST API - Unable to create a custom field of type Text for object Account

Summary:

Unable to create a custom field of type Text for object Account

Content (please ensure you mask any confidential information):

We're trying to create a custom field on the Account Project (OrganizationProfile) using REST API.

Endpoint URL: https://instancename/crmRestApi/resources/latest/businessObjects/OrganizationProfile/child/fields

Headers:

Content-Type : /vnd.oracle.adf.resourceitem+json

Metadata-Context:

sandbox="Custom_Fields"

Body:

{    "apiName": "test_c",    "name": "Test",    "type": "Checkbox",    "displayLabel": "Test",    "description": null,  "updateableFlag": "true",    "defaultValue": "N",    "defaultValueExpression": null,    "searchableFlag": "true",    "updateableExpression": null,    "includeInServicePayloadFlag": "true",    "columnName": "EXTN_ATTRIBUTE_CHAR008",  "dataStoreAlias": "OrganizationDEO"    }

Response:

400 - Unable to create a custom field of type Text for object Account.