@jessejm said in F.lux shows that it's on but the color isn't actually changed.: turn my monitor on BEFORE turning on my PC Then turn your monitor on AFTER turning on your PC ;-)

Huh! Good to know - I guess that's a tick in the "pro" column for upgrading to 10.11, which I'll do once I can make sure it won't cause other problems elsewhere... cheers, j

We have noticed that the NVIDIA card handles color profiles wrong on 10.10.5. This appears to be fixed on 10.11.