Lighting changes randomly after rebuild or movie export

Hi! I have this wierd problem. After rebuilding lights, once in a while some objects will become dark, other obejcts will get strange lighting and spot lights will disapear. Sometimes I must rebuild lights few times in the row, without changing anything in the scene and then after few attemps, lights will fall back to the normal look. It wouldn’t be that much of the problem, but when I’ve tried to export movie via sequencer tool, this problem appeared again.
This is one frame from the movie i was trying to create:

and the next one looks like this:

This is one of my first attemps to create interior scene within Unreal Engine. I know that my lightmaps resolution is probably a lil’ bit too big, but can it be the reason of this behaving? Thank’s in advanced!