I am having the same problem. But i made the light in Corona 8 not 7. When i open the scene the rectangle light is a sphere. When i click the rectangle box the light changes to rectangle, but when submitted to the backburner the slave machine opens the scene with sphere lights making the rendering completely wrong. See attached screenshot!
Edit: 3dsmax 2015
Edit 2:Ok, so what you need to do to reproduce this is place a rectangle light in a scene, xref another file into the scene, close 3dsmax and open the scene, then the rectangle light will be a sphere. It lookes like something is broken with xref's in at least max 2015 and 2016. My other issue regarding the resetting of the tone mapping is also related to xref's. This is actually very bad.
A temporary fix for the lights is to also save the lights into a seperate file and xref that file into your scene, hope this helps people out for now.