I guess thats just the way how stage object work .. if u want to use another camera .. disable the stage object first by clicking on the green check mark icon in object manager ..
Ashish Gupta
Motiongraphics artist and 3d generalist
In that case if you want to hide the wall also u can try rendering a shadow pass from cinema and composite it later in AE or some other compositing program …
There might be another way to do it but i m not aware of that ..