Sometimes when I hear something like that, it’s because the camera is zoomed out just a little bit too far and all you see is a wall…because of a small amount of rounding error for the camera eye.
If you click on the rendering screen, can you tell by the material name what you are looking at? Sometimes it will show a material name that gives us a hint of what we are looking at.
Try zooming in just a little bit to see if that makes a difference.
Or it is also possible that there is a section plane in the model that is affecting the rendering.
Try changing the Use Section Planes setting to see if that makes a difference.
Otherwise, send us the model and we will try it here.