Change Deployment Pipeline Owner

We have a deployment pipeline that was created/owned by an employee who is no longer with the co. I am using below API to change the owner :

https://api.powerbi.com/v1.0/myorg/Pipelines/{pipeline ID}/users

with body:

{
  "identifier": "my email address",
  "accessRight": "Admin",
  "principalType": "User"
}

Using a service account with access to: Pipeline.Read.All Pipeline.ReadWrite.All

but i keep getting:

{
    "error": {
        "code": "ALM_InvalidRequest_AccessToPipelineDenied",
        "pbi.error": {
            "code": "ALM_InvalidRequest_AccessToPipelineDenied",
            "parameters": {},
            "details": [],
            "exceptionCulprit": 1
        }
    }
}

Nobody can see that pipeline except when I look at that pipeline in Postman through: https://api.powerbi.com/v1.0/myorg/admin/groups/{workspace ID}/users

Below options are enabled and account is added to: Service principals can use Fabric APIs Service principals can access read-only admin APIs Service principals can access admin APIs used for updates

What am i missing?

Thanks,