Static lights disappears after build! Help!

Hi there.
I have a problem with light building on unreal engine 4.

After the build of my LVL_01_light (every streamed level had another level with lights only, so I build two levels together at the time) all the static lights are turning off. I’ve tried to build the path, I’ve tried leaving the skydome out of the scene and build, I’ve tried isolating meshes and build but with no good result: the problem persists.
My static lights having “inverse square pixel” off, 350 attenuation and 40 points of intensity.
SwarmAgent starts to build, when it arrives to 100%, it encodes texture and invalidating previously baked light as usual. Then, it shows up log errors where I cannot find any interesting errors. When I start to navigate in my scene, static lights refreshing and they turn off. Indeed, I can see stationary light on.

The general lightmass resolution of static meshes is more than 64, obviously.
Allow static lights on project settings is On. Exposure control is 0. Precomputed visibility and lightmass importance volume are in. I’ve cleaned swarm agent cache and then validated it. I tried to delete intermediate folder in project directory. Nothing works.

Thanks for the help.
I’m working on UE4 7.3 with NVIDIA GeForce 670

Interesting. You may want to post this on Answerhub if you haven’t already, may find more help there.