Uber Request Details API not returning data

Question

I'm seeing an issue with Uber /v1/requests/{request_id} API. Per Uber API doc, I'm authorizing with OAuth 2.0 bearer token with request scope, passing in valid request_id, etc. (My OAuth 2.0 login is working correctly, so I know my access token is valid.)

The response I get is always:

SUCCESS: {
    code = forbidden;
    message = Forbidden;
}

A sample request I'm making is:https://api.uber.com/v1/requests/118f2b74-1bea-4e75-b7de-3b034e5zd811

Using Uber API Sandbox, however, I get a valid response. For example:

URL: https://sandbox-api.uber.com/v1/requests/888d3da2-1433-4a6b-d1d1-e1f1061fe256

Response:

SUCCESS: {
    driver = "<null>";
    eta = "<null>";
    location = "<null>";
    "request_id" = "888d3da2-1433-4a6b-d1d1-e1f1061fe256";
    status = processing;
    "surge_multiplier" = 1;
    vehicle = "<null>";
}

Anyone able to call Uber's Request Details API (both production & sandbox) successfully? Any help would be appreciated.