What is it about the Showdown VR demo project that prevents “Detail Lighting” and “Reflections” view modes from showing what you would normally expect in those view modes? It just seems to render everything as normal lit. If I switch to another project they seem to function normally.
From what you describe you downloaded the Showdown VR Demo from the learning section of the UE4 launcher. When changing view modes to either reflection or detail lighting there is little to no change in the viewport.
I was able to reproduce this issue and it does appear to be a bug. I have reported this to our development team and they will look into this issue as soon as possible.