UPDATE: I'm not sure that it actually did fix it, as today I tried to use the keyboard shortcut to dim the displays and only the secondary display was affected. However turning off "use internal color table" did fix the issue, so it seems just switching that setting on/off solves it.

This seems to be happening only when the second monitor is turned on later on. Because when operating system is booted with both of them already turned on then this issue does not manifest itself

Nevertheless the bug is still persistently present

That is really a new one. Can you post f.lux options > driver info?

Hi @Anakha - can you post f.lux options > driver info?
This issue is usually due to a USB-connected monitor without color controls. We are trying to make a list of all the adapters that fail.

Yes, with the free version, we always do update checks, we just give the option to install them.

In a typical year, we need to do 2-3 releases just to keep compatibility with Windows and driver updates. Some of these issues are pretty serious, and they are mostly out of our control, but we do our best to keep things working well.

Think of it this way: with many millions of users, we cannot handle telling people by hand to go update the software to the latest version - our email just does not scale like that! So if we did not do updates like this, we would have millions of broken f.lux installs and no way to fix them.

We do have a commercial version if you would prefer to receive emails about updates instead - this version never talks to the network automatically:
https://justgetflux.com/corp/

What do you have for a graphics adapter? Intel, AMD, or NVIDIA?

I'm thinking there's some setting in the graphic adapter's control panel that you have to toggle.

Another possible culprit could be Windows. Go into the f.lux settings and turn on "Always use Windows internal color table".

Please add a CheckBox I beg you, in HDR mode the pink/red tint is horrible and looks so bad

Solar time is different from standard time. I could try to explain it, but I recommend doing an internet search for "what is solar time?" It's an interesting subject.

Edit: Also, here's Michael Herf's answer when I asked what solar time is: https://forum.justgetflux.com/topic/7526/what-is-solar-time

It's also explained here: https://justgetflux.com/news/pages/v4/readme/

It says this:

Solar Time?

Solar Time is the time a clock would say if it were based on the sun. If our clocks worked like this, noon would happen when the sun was directly overhead.

We now show Solar Time in f.lux interface, because we think it’s important.

If your solar time is after the current clock time, it’s likely that you live in a place that’s easy for night owls to be (because they can wake up late). And if you’re in a place where the solar time is much earlier than what your clock says, it’s easier for early birds, because they can go to bed early.

@herf Oh that's amazing thank you so much, that worked perfectly! Thanks again for the help. :)

Oh, I see. Thanks :)

@herf Ah right. Windows apps are kept around pretty differently. I see why this decision was made. Regardless, I think people would still benefit from being able to add an EXE name. Under the right click menu item to disable for a specific time or application, would it be possible to add a button to the list that just says "For an exe..." which would open a file picker when clicked on? Adding a program through this method would add an exception for the full path of the executable instead of the window title. The main window title functionality would stay put and this would just be something used by people who want to add the EXE manually because they know what they're doing.

4.119 - still huge usage.
But just got new pc and on this build [pc] f.lux not using much cpu, not at all.

Guess it just not optimized for old hardware.

It looks to me like it's due to your color settings for your display adapter. I'm referring to whatever software is installed for that, whether it's for Intel onboard video, AMD onboard video, or an NVIDIA or AMD GPU which would be either NVIDIA Control Panel or AMD Radeon Software.

Can you take a photo of what you're seeing? To post it, click the Upload Image button that's on the far-right (it's a vertical rectangle-shaped button with the top-right corner dog-eared).