What are these black glitches in my scene?

Can anyone explain these black glitches in the scene please?
I have blocked out a very basic room with BSP brushes. Then I’ve set up a Directional Light and a Point Light (to see the inside better) inside the room.

I’ve rebuilt the lighting already and that didn’t help at all.

I was following this course [https://www.udemy.com/unreale4/][1] and all the assets are part of the ArcVisDemo project that came with this course.

My engine version is 4.15

Thanks in advance.

Hi, i’m interested, I think I have the same bug on a simple box.

I checked the uv2 & the mesh normals and it’s all good, I can’t figure it out.

Set the lightmap resolution to 256 or 512.

as you can see in the overview screenshot, it’s not a lightmap question :confused:
the .uasset is avalable if you curious to see this .link text

did you solve this?

Are you sure about there is no double object at same location? Sonetimes unreal clones object to the same location when you bring them into scene.

yeah, no more black weird glitch in 4.16 ! =)