PowerBI UpdateDatasource Credentials OData not working with REST APIs

[Anonymous]

Hello,

I'm trying to update the data source's credentials of an uploaded PowerBI report via the REST API, but the credentials are still the ones that the report is uploaded with.

After uploading the report via the PostImportWithFileAsyncInGroup I'm querying for the import with GetImportInGroupAsync.

I'm then calling 

https://api.powerbi.com/v1.0/myorg/gateways/{gatewayId}/datasources/{datasourceId}

{
  "credentialDetails": {
    "credentialType": "Basic",
    "credentials": "{\"credentialData\":[{\"name\":\"username\",\"value\":\"..\"},{\"name\":\"password\",\"value\":\"..\"}]}",
    "encryptedConnection": "NotEncrypted",
    "encryptionAlgorithm": "None",
    "privacyLevel": "Public",
    "useEndUserOAuth2Credentials": "False"
  }
}

This call is returning 200, but the credentials are NOT changed.

Notes:

1. There is no Gateway installed, I'm using the default GatewayId that comes with the dataset;

2. The new Dataset is owned by the Service Account which is used with the APIs;

3. To inspect the data source credentials, I need to go to app.powerbi.com and take ownership of the datasource.

Any ideas why wouldn't the credentials update?

Thanks!