Writing some automation through quick controls seems to work fine.
Reading the automation shows somewhat jerky or stuttering visual response on the UI, yet the resulting sound seems to be accurate.
Assigning MIDI remote controller (receive and transmit) to Quick Control seems to break things down:
Writing automation with MIDI controller works ok.
But while reading automation during playback (transmitting parameter values to MIDI controller enabled) the automated parameters in UI becomes very unresponsive, updating maybe once every second or so. Motorized faders on the controller mirror this behaviour also.
It would appear that during playback (automation read only) Quick Controls are still listening the MIDI input from the MIDI controller creating a MIDI feedback loop, as Cubase is transmitting the same parameter values to the controller, which naturally circle back to Quick Controls remote input through the controller. While in read mode, the MIDI controller still controls the Quick Controls parameter values.
Disabling the transmission of Quick Controls parameters to MIDI controller fixes this, and confirms this. Obviously, also disables the parameter transmission function itself.
Disabling the MIDI receive for Quick Controls, leaving only the transmission on, the MIDI controller faders shows same jerky motion as UI, but sound is ok.
To my understanding, while reading automation, the DAW should not be listening for remote control surface input for automated parameters (which are being read).