Hi!
I think before talking about errors and bugs you should understand the lighting in Unreal! You should understand what is static and dynamic lighting to decide which one you need for your scene before completely turning off light calculation as a solution! :S
I advise you to go through this page to clear things out:
But basically as it was said before a couple of times:
if you use static(or stationary) lights your lighting information will be baked into your (static)meshes! Will take just one calculation (BUILDING LIGHTING) and after that it’s on your meshes like a “material”.
And because it’s baked into your meshes whenever you make changes like moving meshes or placing new ones or changing your light properties: you will have to rebuild your lights because there are new information and your scene needs to be “updated”.
Keep in mind that this is the only way right now to get proper GI! You won’t get any from dynamic lighting!!
I hope it clears a few things but read through that wiki page also!!
Good luck!