What is the correct JSON body to disable PowerBi Schedule Refresh via API

This is the example Request body provided by Microsoft to disable a PowerBi schedule refresh via the Rest API

{
  "value": {
    "enabled": false
  }
}

When I call the API, using a service principal, in ADF, with the same request body I get the following error.

{"error":{"code":"InvalidRequest","message":"Invalid NotifyOption
value ‘MailOnFailure’ for app only owner requests"}}

If I amend the Body like so,

{
  "value": {
    "enabled": false,
   "ScheduleNotifyOption":"NoNotification"
  }
}

I get the following error

{"error":{"code":"BadRequest","message":"Bad
Request","details":[{"message":"Value cannot be null.rnParameter
name: nullableType","target":"datasetModelRefreshSchedule"}]}}

The notes on the API state that "A request that disables the refresh schedule should contain no other changes."

Here’s the web activity code

{
    "name": "Disable dataset refresh",
    "type": "WebActivity",
    "dependsOn": [
        {
            "activity": "Takeover dataset",
            "dependencyConditions": [
                "Succeeded"
            ]
        }
    ],
    "policy": {
        "timeout": "0.00:10:00",
        "retry": 5,
        "retryIntervalInSeconds": 30,
        "secureOutput": false,
        "secureInput": false
    },
    "userProperties": [],
    "typeProperties": {
        "method": "PATCH",
        "headers": {
            "Authorization": {
                "value": "@concat(n    string(activity('Get AAD Token').output.token_type)n    , ' 'n    , string(activity('Get AAD Token').output.access_token)n    )",
                "type": "Expression"
            }
        },
        "url": {
            "value": "https://api.powerbi.com/v1.0/myorg/groups/@{pipeline().parameters.PBIWorkspaceId}/datasets/@{pipeline().parameters.PBIDatasetId}/refreshSchedule",
            "type": "Expression"
        },
        "body": {
            "value": {
                "enabled": false
            }
        },
        "authentication": {
            "type": "ServicePrincipal",
            "userTenant": {
                "value": "@pipeline().globalParameters.TenantId",
                "type": "Expression"
            },
            "username": {
                "value": "@pipeline().parameters.SP_ClientId",
                "type": "Expression"
            },
            "resource": "https://analysis.windows.net/powerbi/api",
            "password": {
                "type": "AzureKeyVaultSecret",
                "store": {
                    "referenceName": "LS_KV",
                    "type": "LinkedServiceReference",
                    "parameters": {
                        "baseUrl": {
                            "value": "@pipeline().globalParameters.KeyVaultUrl",
                            "type": "Expression"
                        }
                    }
                },
                "secretName": "xxx"
            }
        }
    }
}

How do I correct this?