stripped down scene, just a camera and the bitmap.
it does it with any bitmap and even when using a new bitmap `map` and new selected bitmap.
something screwy in the scene maybe.
Note: I converted a vray scene to v3 then merged to become v4.
I reinstalled v3, merged `just the camera` from the scene and reapplied a new enviro map and it works fine.
I reinstalled v4 again merged `just the camera` from the scene and reapplied a new enviro map and it`s a blocky mess.
Also tested just loading the scene again in v4, same blocky thing.
attached the scene and a map to test.