Dual External Monitors Not Working in Clamshell Mode After macOS Sequoia 15.6.1 Update (MacBook Pro M3 Pro)

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Dual External Monitors Not Working in Clamshell Mode After macOS Sequoia 15.6.1 Update (MacBook Pro M3 Pro)

Hello,

I am facing an issue with my MacBook Pro (M3 Pro, company-issued) after updating to macOS Sequoia 15.6.1. My setup has been working perfectly for the last 6 months, but since the update:

• With the lid open, both external monitors (1 via HDMI, 1 via USB-C) work correctly as extended displays.

• With the lid closed (clamshell mode), only one external monitor is detected—the second freezes or goes black.

• If I temporarily use Sidecar (iPad as 3rd display), all three displays work, but as soon as I stop mirroring, the issue returns.

• Cables, monitors, and ports are all tested and confirmed to be working.

This appears to be a regression introduced in Sequoia 15.6.x, as multiple other users have reported the same on Apple forums. For example: Apple Support Thread – External monitors turn off in clamshell on Sequoia 15.5.

I rely on a dual-monitor setup for my work as a software engineer, and this issue is impacting productivity.

Request:

• Please confirm if this is a known bug in macOS 15.6.x.

• Is there an official workaround or fix available?

Thanks,

Tushar

[Edited by Moderator]

MacBook Pro (M3, 2023)

Posted on Aug 31, 2025 06:07 AM

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Answer 1

Top-ranking reply

den.thed

Level 10

88,654 points

Aug 31, 2025 07:25 AM in response to _tush

_tush wrote:

I am facing an issue with my MacBook Pro M3 Pro after updating to macOS Sequoia 15.6.1.

This is Apple's user to user forum and Apple does not respond here.

can Apple prioritize a patch in an upcoming 15.7 update?

To send feedback directly to the Apple folks.

Feedback - MacBook Pro - Apple

Feedback - macOS - Apple

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Answer 2

Owl-53

Level 10

100,087 points

Aug 31, 2025 07:47 AM in response to _tush

OP wrote " I am facing an issue with my MacBook Pro (M3 Pro, company-issued) "

A company issued computer with issues that do not meet the employee's needs is better addressed by the Company IT Department

Explain to them what and how the computer is setup and what your specific needs are

They may or may not know something we do not know

After all , they are responsible to support their equipment and the employees needs

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Answer 3

_tush Author

Level 1

4 points

Aug 31, 2025 08:50 AM in response to Owl-53

No setting or restriction set by company, The issue start occurring when I update my macOS version to 15.6.1. Because before that I am using same laptop more than 6 months with same dual monitors setup and It is working absolutely fine before.

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Answer 4

Owl-53

Level 10

100,087 points

Aug 31, 2025 09:28 AM in response to _tush

_tush wrote:

No setting or restriction set by company, The issue start occurring when I update my macOS version to 15.6.1. Because before that I am using same laptop more than 6 months with same dual monitors setup and It is working absolutely fine before.

Most Companies that Issue computers to employees do Manage their computer via some type of Mobile Digital Management service like Jamf, iTunes or some other MDM Service

To say " restriction set by company " seems odd or unique to your Company

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