That should just happen by default. Does AMS 2 have a key to disable monitor view? I can't remember, but if it does maybe you've pressed it by mistake?
I have no idea , but for me the monitor is black , just curious how to turn it on. Is this within the game or in oculus settings?
In some games/sims (like RaceRoom) it's an bindable option in the menus. However, I've just checked and AMS 2 does not have this option. So I'm afraid I don't know why it isn't displaying on your monitor. It always has for me... it's how I capture VR gameplay videos.
i would google for a tweak to shut monitor view off. Some guys ask for that function as they think this would get theme a few frames more. Maybe you tweaked it and forgot about it.
In my experience both in Project Cars 2 and Automobilista 2, the monitor shows the menus using regular desktop view, and then switches to showing the left eye view of my headset as soon as I enter the car in the pits or in a race. I run the game in window mode and not fullscreen, if that makes any difference? (SteamVR and Pimax headset)