PATCH /conversations/voice/{id} 403 when updating participant attributes

NICE CXone API & Integrations
1

Trying to push custom attributes from our CRM into a live voice call. The PATCH request to /api/v2/conversations/voice/{conversationId} returns a 403 Forbidden, even though the token has admin:conversation:write scope.

{
 "participants": [{
 "id": "123",
 "attributes": {"crmId": "999"}
 }]
}

Any idea why the scope isn’t enough?