OpenSearch Updating plugins.ml_commons.only_run_on_ml_node not working

I've recently updated to OpenSearch_2_5_R20230308-P4 and I am no longer able to set only_run_on_ml_node.

To reproduce, create a new OpenSearch instance with the version above, and make the following request to the API:

PUT _cluster/settings
{
  "persistent": {
    'plugins.ml_commons.only_run_on_ml_node': false
  }
}

The output is:

401
{"Message":"Your request: '/_cluster/settings' payload is not allowed."}

I am able to update other settings, so I know it's not an authentication issue.

Also, I am able to make the above request on an instance running with R20230308-P2, so I suspect this is due to a recent update.

I have the following questions:

1. Is there a way I can make this request?
2. Are there any release notes that explain changes to the AWS hosted OpenSearch service? I looked in the official OpenSearch release notes but I think these are AWS specific changes.

Thanks in advance.