When i load x plane vr in steam and start in the hangar i have a normal full image 

Then i start a flight in the cockpit and i have a picture in picture mainly on the left eye

I deinstalled steam vr and reinstalled did several times the room setup problem still exist

 

You maybe able to run room setup again and find something that is not quite right. To get to room settings right click the SteamVR icon and click room settings. I put this up as some of us are really not use to Steam, I know I had to stumble around in Steam for awhile LOL

Solved it:

It was the plugin blu_fx (thanks to JLSeagull)

My plugins are: Better Pushback(working in vr)

                          Terrain Radar(working in vr)

                         Headshake(working in vr)

                          X-Raas(working in vr)

                          X-Weather(not working in vr)

                          X-Cecklist(not working in vr)

                          Airport Navigator(not working in vr)

                          Fly with lua(?????)