When video card drivers are enabled in the device manager f.lux works in the backround, but doesn't change the color. When I disable the drivers f.lux works changes the colors.
NVIDIA 18.104.22.1681: NVIDIA GeForce GTX 1050 (20190130)
Generic PnP Monitor, 477 x 268mm, built 2013
sRGB gamut: 82%, AdobeRGB gamut: 58%
Windows Build: 18317