Actually we have an update as of today (messages just passed eachother it seems). PTZ control has never been implemented for Management Client environment and unfortunately this is not stated in the documentation.
We will make sure that it is implemented for the 2021 R1 release (as 2020 R3 is already closed ).
Also does not seem to work in the Smart Client environment when using the Messaging API. I did some testing using the MessageTester SDK sample and could not get it working.
Hmm maybe I misunderstood you because that is also what I suggest you should do (either SendMessage or PostMessage). I thought you meant that using MessageCommunication did not work.
So are you saying that using EnvironmentManager.Instance.SendMessage for PTZ in Smart Client does not work?