Environment map goes black when using multiple WebGLRenderer

I took a lot of time to debug why the environment map is black when using RGBELoader.

Like this one, OP didn’t even find the cause.
GLTFLoader and RGBELoader - Adding HDR texture to the environment

In my case, it turned out that it was caused when I was using 2 WebGLRenderer at the same time and both with texture shaders.
Both WebGLRenderer has nothing shared on the application layer.

What could be the possible cause of this issue?
And how to solve them?

Could you share more detail on what this means? Also – are you using scene.environment or material.envMap? I don’t think this issue is expected…

I’m using scene.environment.

Here is the minimum example I could produce. Codepen Link
You can try commenting out a canvas.
Each of them is working but not both.

Here is the update live example: three.js dev template - module - JSFiddle - Code Playground

I have just removed the post processing code and now it is working. So there must be an issue with the postprocessing /realism-effects packages.