I'm using an account with the client id and client secret to call the Transmittal API and it returns error 403 forbidden with "access deny" error.

https://developer.api.autodesk.com/construction/transmittals/v1/projects/{projectid}/transmittals

{
    "code": "ERR_NOT_ALLOWED",
    "title": "Operation not allowed",
    "detail": "api access deny"
}

but no issue when calling RFI API under using same account and same projectId.
https://developer.api.autodesk.com/construction/rfis/v3/projects/:projectId/rfis

{
    "results": [
        {
            "id":..
        }
    ]
}