Actually, I think I’ve isolated a related problem, which is that the OutScreenVector property of the HeightFogVertexShader.usf is resulting in unexpected data.
I think this is because line 22 of the HeightFogVertexShader is now:
OutScreenVector = mul(float4(InPosition,1,0), ResolvedView.ScreenToTranslatedWorld).xyz;
when it used to be
OutScreenVector = mul(float4(InPosition,1,0), View.ScreenToTranslatedWorld).xyz;
the ResolvedView.ScreenToTranslatedWorld seems to failing.
Fixing this line (changing it to View.ScreenToTranslatedWorld) seems to result in fixing the heightfog. Although I bet this probably breaks for stereo…