Two things:

We keep the device awake for Philips Hue, but there is an Options menu checkbox to turn this off, so it will sleep and stop updating your lights. The default is to stay awake.

Also, if the device is on battery power and charge is below 66% we allow it to sleep, so this mostly applies to plugged-in devices.

We stopped looking for changes to color profiles frequently, due to a major memory leak in Windows May 2019 update. If you change color profiles, you now have to restart f.lux (or wait an entire day for us to check).

@ffuxi Great idea, I am missing this ability as well.

You have to turn off Windows Night Light.

Interesting, I was unaware of the corporate build. $15 seems perfectly reasonable for a personal license, I think I paid $50 for Actual Window Manager.

It appears f.lux has updated itself again to 4.104, and the full screen issue is fixed. The second issue I mentioned might have happened on the new version, or it might have happened as f.lux updated itself to the new version, but since I don't have control over updates, and f.lux doesn't report when it last updated, I have no way of knowing. It is a basic requirement that I be able to freeze versions of software on my computer, in part so that I can give accurate feedback and bug reports.

I uninstalled FLUX cause of this..

It can conflict with other apps in the system, but generally it should work fine with any number of monitors.

There is a feature to disable for all fullscreen apps. Double-check in f.lux menu > Disable to see that it's off.

Issue solved. Not sure about the reason but I upgraded from Windows 10 1709 to Windows 10 1809.

Just came here to suggest this as well. f.lux just updated for what seems like the third time this week, and either it always happens to update at night or I just notice when it does, because the screen will suddenly become very bright. It's been 11 months since this thread was started and this still hasn't been implemented, even though it seems it should be a fairly easy thing to do. I understand time has to be allocated and prioritized, but this seems like a fairly big ROI improvement in terms of user satisfaction vs time needed to do it. Anyways, I hope you'll consider making it more of a priority.

Set 1200K for day, night, and bedtime. You'll need to enable the wider slider range for this.

Because I haven't heard from anyone else about this yet (we have lots of NVIDIA users!), I would also make sure the audio drivers are current - perhaps it could be on that side too. Can you see if there's a newer sound driver available?

Our 4.101 beta is doing even more aggressive caching of the leaky call, should show slightly lower numbers.