Is it only with that game? Or every game
I just realized what it might be. The auto sleep function is currently apparently broken, the toggle doesn't work. So it's always on. And it works by counting frames and after a certain number it makes the model sleep. So maybe when you switch to a game, the monitor fps syncs and increases or something triggering the model to sleep sooner.
You can try limiting your games/monitor to 60fps. Otherwise, I will be fixing the toggle and adding an option to define how long before a model goes to sleep which should solve the issue in the next update.