Objects shine like supernova with no light present

Hello, I’ve posted this in rendering already, but this might be a better place for it.

I’m quite new to Unreal and this is my first real project in it. I’ve been testing some stuff previously etc but never actually done the texturing etc in it.

I’m working in Archviz (blank template) and when I disable sun/put intensity on 0, the objects (all objects, not just the stuff I imported) starts to randomly shine until the entire screen is white from them, then when I put sun back to default value the shine goes down and it’s all normal. Same happens if I have some lights already set up on the scene and if I don’t have any lights. I tried removing the sky/sun as well along with all other light sources and the same happens.

I’ve already tried a bunch of things that I found out by googling “Objects shine with no light source”, “Objects on scene start to glow when light is off” etc, nothing really helped.

I don’t know if this is of any relevance but the materials were made in Substance and Exported for Unreal 4. Unreal version that I’m using is the current newest. No custom plugins.

Is there a way to properly get rid of this?

Picture 1: Scene stays dark for a few seconds after putting sun intensity to 0.
Picture 2: But a few seconds later it starts glowing like insane.

Thanks!