I have some mountains in the distance that I’d like fogged out, but SSAO renders on top of the fog. It looks pretty much like a bug. Any workarounds or is this a bug?
I also have this problem, were you able to find a workaround for this at all?
Perhaps try using the Global Fog effect instead of the builtin fog? Try and play around with the order of image effects when you try that, sometimes SSAO will render on top of Bloom or DOF if it’s lower than them. Also your scene looks very pretty outside of those artifacts! 
Could possibly add a member variable to SSAOEffect.cs that stops rendering SSAO at a certain distance. I haven’t tested this and haven’t dug too deeply into the script’s functionality, but on line 106 of the file there is this:
float far = camera.farClipPlane;
perhaps manually setting the “far” variable here to some distance that is shorter than where the fog makes this an issue would fix it?