Can someone please explain to me what the heck is going on here and how to fix this? Pretty please?... :/ Everything is fine with iRay but now with the octane

Hello, i will be quick here. When I press F12 and open viewport, all I can see is one small square in the center, loading bar above loads very quickly and only when I start final render is when I see full picture. How can I fix this? This used to be fine yesterday but I think I messed up with the ...