3731999 - Sharing DB Instance with DB Tenants with other Subaccount is failing

Sharing database instances with other BTP subaccounts is supported by the SAP HANA Cloud Admin REST API is failing:
Share a Database Instance with Other Subaccounts Using the REST API | SAP Help Portal
https://help.sap.com/docs/hana-cloud/sap-hana-cloud-multitenancy/share-database-tenant-with-other-subaccounts-using-tenant-management-service-rest-api?ai=true

While Getting and Creating Instance Mapping, encountered below error messag:

################## STEP : Get Instance Mapping  
GET {{gateway_url}}.{{host}}/inventory/v2/serviceInstances/{serviceInstanceID}/instanceMapping
Authorization: Bearer {{bearer}}
Custom-Header: valid_value

got the following error:

HTTP/1.1 404 Not Found Content-Type: text/plain; charset=utf-8 Content-Length: 19 Connection: close X-RateLimit-Limit-Minute: 2000 RateLimit-Remaining: 1999 X-RateLimit-Remaining-Minute: 1999 RateLimit-Reset: 4 RateLimit-Limit: 2000 x-content-type-options: nosniff date: Fri, 23 Jan 2026 11:07:56 GMT x-envoy-upstream-service-time: 2 server: envoy Strict-Transport-Security: max-age=63072000 404 page not found

################## STEP : Create Instance Mapping - Subaccount
POST {{gateway_url}}.{{host}}/inventory/v2/serviceInstances/{serviceInstanceID}/instanceMapping
Authorization: Bearer {{bearer}}
Content-Type: application/json
Custom-Header: valid_value
{
    "platform": "subaccount-api-access",
    "primaryID": "f3554543-7030-4e3c-a305-c4a2b575dba2"
}

got the following error:

HTTP/1.1 404 Not Found Content-Type: text/plain; charset=utf-8 Content-Length: 19 Connection: close X-RateLimit-Remaining-Minute: 1999 RateLimit-Limit: 2000 RateLimit-Remaining: 1999 RateLimit-Reset: 28 X-RateLimit-Limit-Minute: 2000 x-content-type-options: nosniff date: Fri, 23 Jan 2026 11:11:32 GMT x-envoy-upstream-service-time: 1 server: envoy Strict-Transport-Security: max-age=63072000 404 page not found

• SAP HANA Cloud Database

SAP HANA Cloud, Instance Mapping , KBA , HAN-CLS-HC , HANA Cloud Services HANA Cloud , Problem