The black thing in your image - what are you intending it to be in the end? Water?
I think it has flipped normals. Can you try applying "normal" modifier to it?
Corona 4 is more sensitive to normal direction than the older versions. If you are creating something refractive or volumetric, make sure that:
- it is a solid object with some thickness (for example: a box instead of a plane, a sphere instead of a circle, etc.)
- the normal directions are correct
The easiest way to check normals direction is to select your offending object, right click > object properties > enable backface culling. If the normals are correct - the object will appear shaded in the viewport. If the normals are flipped, it will be invisible (fully transparent).
Hope that helps!