If you are using Command and Control, we discovered that the templated code for Read Command is actually sending the Reserve Command to the Controller.
The diagram constant that should be set to Read was generated with Reserve instead.
In 2018, there is an interactive command loop next to the controller that periodically reads and optionally posts an interactive command. Because of the issue with read, and the read in the interactive loop, this can lead to to canceled commands. Also, the spamming of reserve commands raises CPU usage.
The solution is to open the Read command of each generated subsystem and ensure that the diagram constant is posting a Read operation instead of a Reserve.