I've recently become obsessed with building faster and more capable rovers, mostly for use on Kerbin. I have always done testing on Kerbin in the day and have never needed to use my lights. Once I got one of them to the Mun I noticed that the lights would only light up other craft and the rover itself. This was also true on Kerbin. Below are some images for greater depth of understanding. As seen in the first and last image, the lights do not shine beams but only illuminate the rover... not that helpful.
I have tried on different craft and saves, I even reinstalled the game. Finally, no, my lights are not stuck behind a structural component.
If you have experienced this yourself or have a solution, preferably the latter, please let me know.