There use to be a Light/Dark option under the 'features' tab for an object. This is missing in the latest version of Quest.
Has this option been moved to another park of this program?

There's an option to enable light/darkness on the features tab of the game element. Once that's enabled, it will appear on the features tab for each room or object.

Thanks mrangel, that solved the problem.
I didn't think this option would be left out of the game.