[BUG] Cloning picture with Daisy Chan through DisplayPort applies f.flux only for one monitor out of two



  • I recently bought a brand new ACER XR382CQK bmijqphuzx (UM.TX2EE.009) monitor to replace its predecessor Acer XR342CK bmijpphz (UM.CX2EE.01). I played with them around by using them both simultaneously in some configurations. And what I have noticed is this:

    If I copy picture from one monitor to another by using Daisy Chain option Clone and a DisplayPort cable, then only one of the monitors will have f.lux working - the first one that was turned on [the original one]. And with the very same setup I can close f.lux completely and use instead of it the operating system's option available at

    Settings > System > Display > Color > Night Light > On

    This OS built in feature works flawlessly with my Daisy Chain experimental set up. And f.lux does work for two screens at the same time- when I use an extended desktop mode. [I have not checked out the Picture-By-Piture or Picture-In-Picture modes]

    ERGO: there is some bug in f.lux

    I am running f.lux 4.119 on Windows 10 Enterprise 20H2 19042.746



  • 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


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