BIOS settings URI

No, I would not expect that to happen at all.

If the property in question is only writable in the active resource, then the property is not supposed to exist at all in the settings resource. A client attempting to modify this property in the settings resource would get an unknown property message.

If the property in question is writable in both the active resource and the settings resource, the property will only exist in the settings resource if the client has already made a request to modify the property in the settings resource. If the client has never attempted to modify the property in the settings resource, then it will not exist in the response. However, a client can come in later and apply a value to the property in the settings resource; the service is not expected to reject this request.