External display turning off in clamshell mode macOS Tahoe 26.5

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External display turning off in clamshell mode macOS Tahoe 26.5

I am on the 14in M1 Max MacBook Pro running macOS Tahoe 26.5. After the update, I can no longer use my external display while in clamshell mode. I didn't change a thing in my setup; it worked perfectly fine for months until I updated the OS. I am using Anker's Thunderbolt 4 docking station and connected to my display via DisplayPort. I have a wireless mouse and keyboard that are plugged into the docking station via a USB dongle. This setup has worked for me since I got my laptop, but after this update, I can't strictly use the clamshell mode. The extended display works, but I want the monitor as the main and the laptop closed elsewhere, like it always was.

MacBook Pro 14″, macOS 26.5

Posted on May 31, 2026 11:13 PM

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Answer 1

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neuroanatomist

Level 9

58,653 points

Jun 1, 2026 4:29 AM in response to Shlumpz

Did you upgrade directly from Sequoia?

macOS has become progressively less tolerant of video data packet loss due to sub-par cables. There have been several reports of setups that worked in Sequoia not working in Tahoe, with nothing changed but macOS.

Best recommendation at this point is to try a new cable. Be sure to use high quality cables – HDMI should be labeled Ultra or Premium, USB-C cables should be rated for high-speed data transfer, etc. Also, cables should be as short as possible (≤1 m for most cables, <0.5 m for Thunderbolt 5 cables). That random cable you found in a drawer might or might not work.

FWIW, I have two 16” MacBook Pros (M1 Pro and M4 Pro), both work fine in clamshell mode (which is how I typically use them) via a Stone Pro TB3 dock connected to an LG 5K:2K display with TB3. Both Macs are running 26.5.

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Answer 2

Jun 1, 2026 4:12 AM in response to Shlumpz

I do not use clamshell mode habitually, but as I had a keyboard, mouse and display, I tried this (14" M4Pro MBP), and it also did not work. There may have been some change in 26.5. You should add your report to feedback:

https://www.apple.com/feedback

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