Hello
To see some parts of my scene in Cycles I use “ctrl alt b” and “ctrl b” to select and see materials eyc…and everything is fine.
But here when I’m back in “solid” vewport you can see that my preview square is as projected and making a sort of boolean about the scene 
I tried to delete all the cameras…
I reboot Blender
I used ctrl alt b…
Nothing change 
