Does anyone know how to solve this issue with the sun lens flare being displayed through clouds, aircraft, terrain?

I have reset my original shaders and reinstalled the Prepared Install Client used the default sun textures and suneffect.cfg, however it doesn't seem to have an effect.

I'm not too sure what happened since if I recall correctly, the sun lens flare seemed to be working normally a few weeks ago and didn't shine through clouds.

 

Why wouldn't it? It's *lens* flare. It's a simulation of visual artifacts within the lens of a camera. The lens flare isn't influenced by what object is in front of the camera - it's influenced by where lights are.

Now, if you mean that the sun is behind the airplane and you see a lens flare anyway, then unless the lens flare system also takes into account things like runway and landing lights, that's an issue - can you clarify?

Personally, I turn lens flare off because my eyeballs aren't cameras and aren't subject to lens flare, and therefore the effect is unrealistic.