Plane: Uber Coating set to reflect the cubes above
Cube 1: Uber shader with Transparency = 1
Cube 2: Simple Diffuse cube
Cube 3: Simple Diffuse cube with RPR Settings Casts Shadows + Camera Visibility turned off.
Cube 4: Same as Cube 3 only with another Sphere object dissecting the Cube - showing the "darkening effect" of the supposedly invisible cube.
Cube 1: Cuts a hole in the plane displaying the background colour of the scene. It should not do this.
Cube 2: Correct
Cube 3: Should not display a reflection or cast a shadow.
Cube 4: As Cube 3 but it is also darkening the sphere as if it is casting a shadow.
All of these issues above also exist on any Simulation Domain box.