Spectral Rendering Conversion Intent
If I change this from 'faithful' to 'natural' and have Environment Mode set to Scene Only, no light appears in Iray Viewport.
All I have in the scene is G8F and a default Spot Light (with 500000 Lumen).
If I change the light geometry from Point to Rectangle, I get a *little* light, but doesn't make sense why that would have such an effect. Any ideas?

Comments
I'm going bonkers trying to find the answer to this too, but no one seems to know.
I have four lights staged lighting up my character and I'm using a HDRI background set up as a finite sphere wiyh ground. All lights work perfectly when I have spectral rendering set to faithful, but as soon as I switch to natural, it turns all my lights off - ARGHHH!!!!!!!!
I much prefer the naturalistic photographic rendering that the 'natutral' Spectral intent gives me, but why the heck can't I still have my fill lights?!?!?!?!! HELP