There is one Scene Depth that is most important (out of all those 0.0001 fractions of the 2^24-1).
And that is the Depth from the camera to the BP_SkySphere.
Honestly we can’t use this buffer for anything here while making architectural animations out of Unreal. If there could be a setting somewhere in Project settings → Rendering then that would be awesome. Also I am quite sure that when you render out a movie the Z-depth could easily be in HDR.