Not working after Windows 10 (1909) update
I tried exploring fixes from the 1903 May update issues, so Night Light and Fast Start-up are both disabled. I've uninstalled and reinstalled f.lux and have restarted several times before and after checking for Windows updates. F.lux was working fine before the update, but now will not change the screen color at all. Driver info pasted below:
Advanced Micro Devices, Inc. 25.20.14136.0: AMD Radeon(TM) Vega 3 Graphics (20190227)
Generic PnP Monitor, 344 x 193mm, built 2016
sRGB gamut: 86%, AdobeRGB gamut: 60%
Monitor 1 on AMD Radeon(TM) Vega 3 Graphics: VCGT=0 gamma=1
Windows Build: 18363.720
Had the same problem, tried everything I could from 1903 threads: install and uninstall countless times, update drivers, downgrade drivers, upgrade again, regedit cleaning, Fast Startup disabling, etc.
Eventually I tried uninstalling the Store app and then installing via executable --> immediately worked! Hope this solves your issue.
Latest download is found here: https://justgetflux.com/dlwin.html