How to fix mesh backside not showing properly?

Hello I am using UE 4.26. I am a complete beginner in this engine. But, I managed to make a sci-fi room. But I am facing the problem below.

From inside everything is working well.

But when I go out for the exterior the walls and the celling get transparent like this.

I am using Modular SciFi Season 1 Starter Bundle (Modular SciFi Season 1 Starter Bundle in Environments - UE Marketplace)

My Specs:-

  1. Intel i3 9th gen 4 cores.
  2. 8 GB Ram.
  3. Nvidia Geforce Gt 710 2GB graphics card.

Find the material for those meshes and check two sided:


You can often check this in the material instance.

If that fails, the meshes don’t have UVs on the back.