mmm, just spent ages trying to figure out why the sunlight "xyz handles" had vanished without trace and eventually sussed that it was because I had "hide objects" selected. Why does this remove the handles, when the sunlight object itself is still present? Seems a bit odd.
Hang on - the sunlight has XY+Z handles. Is ths new?
Probably because the sun is a "light" object, the code goes to hide the bounding box etc from it. But then when told to do preview window the lighting is ignoring that fact and using the lighting objects. (since i'm pretty sure when you say disable objects you probably mean on objects tab).
Easy thing to not notice, its impossible to tell the sun even has moving guides usually.
But a semi bug non the less that planetside should maybe look into what is the preferred option in this odd case.
What is needed is for TG to distinguish between .obs, tgo's etc. that can be populated and the inbuilt objects such as the sunlight object or the water object, so that they remain untouched when the hide option is selected for objects.