WHY DOES THIS HAPPEN?

[quetillo]

I don't have Lod installed, on one side it is visible, on the other it is not, it is created in Blender

 

[Mickstix]

You can clone, then flip the normals. Or put a .01 shell modifier on them. The game only sees faces from 1 side, or sometimes known as back face cull. (At least that's what I think it is. I use 3dsmax, not Blender)

 

[fughettaboutit]

you could do this in CSP ext_config.ini

[SHADER_REPLACEMENT_...]
MATERIALS = your material
CULL_MODE = DOUBLESIDED
DOUBLE_FACE_SHADOW_BIASED = 1   ; use this if shadows are also bad
PROP_... ksAlphaRef, 0.5   ; if not already set, 0 would do blocky shadows

General – Shader replacements

Configuration files for Assetto Corsa Custom Shaders Patch - ac-custom-shaders-patch/acc-extension-config

github.com