Can you check your time and your location? Also since you said UK, I think there may be a bug if you are exactly at 0 longitude - if you can push it over to 0.1 it will work better for now. We will fix this.

If that doesn't help, here is a tool to verify your time setting: https://justgetflux.com/timesync.html
(the number should be small)

The older version should be downloaded automatically from the homepage. Which browser are you using?

The direct link is here:
https://justgetflux.com/mac/FluxSnowLeopard.zip

I will try when I would have a cable…

Based on further research, I suspect that this is impossible with OS X. Flux requires a digital signal to the monitor so it can control monitor color settings.

The Mac Pro has multiple digital DVI and USB ports. But the DVI ports all send the SAME image so they cannot be used concurrently to drive multiple screens with different images.

And the USB ports send only a data signal that lacks monitor control of things like color settings. So even if they're transformed and connected digitally, for example with HDMI, Flux doesn't control the monitor color.

One solution to this problem would be for Flux to optionally control colors by directly changing colors in screen buffers, but that would be a major engineering change.

Am I wrong?

@lorna Thank you for pointing me to that! I try not to update my pc too often so I'm still running 15063 and haven't seen the update in the resource you sent. I will update tonight and try it out!

Yeah, that makes sense. Personally, I don't mind that imprecision and tried (out of curiosity) to make a tool to do this myself... and discovered that the location field doesn't seem to allow copy-paste, so I'd have to type in the coordinates by hand...

Anyway, I also learned that OS X Night Shift does approximately what I want with zero friction if I just give it a manual schedule (I don't particularly mind if it's not synchronized to sunset), so I'll probably just use that instead.

No updates, sorry - though the newer model Macs probably have the option to use DisplayPort over USB-C.

@kisaraksu It looks like your f.lux location is set to Australia. For example, 37.767,-122.497 is in Golden Gate Park, in San Francisco. Try clicking the arrow next to Location or enter your nearest major city.

I think this is a fantastic idea. I would use this for many reasons.

your problem is not to do with f.lux , its becaise bad display port cable, try buying a new one.
I had same problem and solved buying a good dp cable.

cheers

Can you post the version of macOS and the version of f.lux?