Building lighting results in pixelated shadows

Hi, has anyone experienced this before? i’ve exported the meshes to blender and checked its normals and everything is fine. I don’t understand how a basic cube static mesh can cause these errors:

Usually, i’ll just let the unreal engine do the mapping for me , by unwrapping the uv automatically using the option shown in the image below, i was surprised that it didn’t work out as expected this time. Thanks!

Oh, another question, is there a way to solve the problem of misaligned textures after i’ve aligned the texture properly on a BSP brush and converted it into a static mesh? Because everytime i convert the texture into a static mesh, the texture becomes huge after i automatically unwrap UV. The way that i’ve currently fixed it is to create a new materials instance and realign the textures.