Hi everyone, this issue im having is a though one, seeing as it is difficult to pinpoint exactly where the issue lies. I will try and explain all the details.
So, we have written our own viewport class, allowing us to have a splitscreen setup rendering three cameras/screens all on the same horizontal axis. In the pictures you are actually seeing three cameras rendering, the cameras are at the same location only with a 60 degrees rotation difference from eachother.
In the first picture it is being rendered without any fog. All three viewports are correct. In the second picture however, fog is turned on and this is when things get weird. This is an exponential height fog being used. In relation to where the directional light is the three different viewports start to change color (to me it looks like its the fog color and maybe the horizon color of the skymaterial that is changing). When the camera is not facing the directional light this happens, meaning that the three different views will toggle between correct lighting/colors and go to this blackish thing when I tunr around with the pawn.
Some of things ive tried with no success:
- Turned of SSR
- Everything turned off in PostProcess volume
- Altering values within the ExponentialHeightFog, especially start and end distances
- Moving the three rendering cameras so that they do not interfere with eachother
- Using the standard ViewportClass with a 3way vertical setup (1 screen on top and 2 on the bottom)
- Eveything turned off on each camera
This level works fine if I only use 1 camera, I.E no black colors, I can use the Fog just fine. As soon as I introduce more cameras at the same time something breaks. So im unsure if this is due to the fog or multiple cameras.
So Any suggestions would be appreciated 
Cheers!