Never mind (but maybe this will help others who experience same problem). I had Sidebar set as I always do - to display on right side of my screen. When I set up iPad as SIdeCAR extended display, I set it up on the right - so my Sidebar was being instructed to be there. If you move Sidebar to left or bottom it will show up back on laptop where I want it. Unfortunately, you can't have Sidebar on right side of laptop screen (as I am used to) if you have extension screen to the right side. So your choice is to move Sidebar to bottom or left OR switch your iPad extension screen to the lefthand side and you can have your Sidebar on the right of your laptop. Hope this helps if others get confused as I did.