Updated to Sequoia 15.5 and dual monitors stopped working

I'm using a Mac Mini M2 with 2 LG UltraFine 4K monitors. Both worked before I upgraded to Sequoia 15.5 tonight.


  • "No device connected" in system report.
  • I've unplugged, checked connections and switched the cable between the two from an Apple Thunderbolt cable to an OEM Apple USB C cable and back with no luck.
  • The 2nd powers up because a Satechi hub is attached and charging my iPhone.
  • Display > Option + Clicking detect monitors does not work.
  • Resetting, sleep mode and turning off entirely have done nothing.


An hour ago I had twin monitors. Now I have one and my organized desktops are now smashed together.


Anyone else have this issue?


Mac mini, macOS 15.5

Posted on May 19, 2025 7:41 PM

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Question marked as Top-ranking reply

Posted on Jul 4, 2025 11:20 AM

Well I went shopping in my garage and found a USB-C to Displayport cable and it seems to work fine. What's crazy is the usb-c to HDMI cable that worked fine 2 hours ago before I upgraded, doesn't seem to work on either of my M1 or M2 Macbooks. One running 14.0 and the other 15.1.. Could the cable have died during reboot for the OS update???? I have two new different brand, Anker and Amazon basics USB-C to HDMI cables on the way to try. Normally I'd just call it fine with the USB-C to displayport cable I am using, but I have a dual HDMI KVM switch I am using with another machine. And I don't want to have to switch monitor inputs everytime I switch computers. I'll update this when I get the cables in a few hours and test.

5 replies
Question marked as Top-ranking reply

Jul 4, 2025 11:20 AM in response to TrickyT1

Well I went shopping in my garage and found a USB-C to Displayport cable and it seems to work fine. What's crazy is the usb-c to HDMI cable that worked fine 2 hours ago before I upgraded, doesn't seem to work on either of my M1 or M2 Macbooks. One running 14.0 and the other 15.1.. Could the cable have died during reboot for the OS update???? I have two new different brand, Anker and Amazon basics USB-C to HDMI cables on the way to try. Normally I'd just call it fine with the USB-C to displayport cable I am using, but I have a dual HDMI KVM switch I am using with another machine. And I don't want to have to switch monitor inputs everytime I switch computers. I'll update this when I get the cables in a few hours and test.

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Updated to Sequoia 15.5 and dual monitors stopped working

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