I have the same problems with my 2019 Impreza. It responds sooner if I'm not in reverse, but I am usually in reverse first because I need to back out of my garage. It usually doesn't respond to the volume knob messages until a second after shifting into forward. I say "messages" because the turns of the knob appear to be queued up somewhere, but it doesn't have as much time to process those while it's displaying the rear-view camera on the screen.