I just surprisingly find that only one of my two external monitors gets Night Shift effects. Can anyone tell me how I can make both work with Night Shift?

  • MacBook Pro (15 inch, 2017)
  • macOS 10.14
  • Both monitors are LG Ultra HD (27', 4K), connected with USB-C <-> mini DP cable.

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1 Answer 1


As the linked answers mention, disabling + re-enabling Night Shift seems to make things work fine. That said...

My guess is that "Night Shift" works by modifying the display profiles for monitors (certainly works that way for f.lux, you can see the display profile change in System Preferences). This happens on my system, and my suspicion is that I have two monitors with the same name (and EDID info, which is probably the actual identifier) => macOS can't figure out that both monitors are supposed to get the display profiles updated, and only one works correctly.

screenshot of doubled Display profiles

  • It seems that disconnecting the monitor and reconnecting it again removes the fix. Disabling and re-enabling is a temporary solution. OS: Monterey version 12.0.1 Secondary display: LG UltraFine Dec 16, 2021 at 3:12

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