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Aref Ha
User level: Level 1 (20 points)

Mission Control dissolves Stage Manager groups in macOS 27.0

Title: macOS 27.0 — Mission Control dissolves cross-application Stage Manager groups


Environment

  • macOS 27.0 Golden Gate
  • MacBook Pro M3 Pro
  • Built-in MacBook display only; no external displays
  • macOS 27 was installed as a clean installation
  • Stage Manager enabled


Problem

When two or more applications from certain applications are manually placed into the same Stage Manager group, entering Mission Control and then exiting Mission Control without selecting another window causes the Stage Manager group to be dissolved.


The applications remain open, but they are separated into individual Stage Manager items instead of remaining in their original group.


This occurs even when nothing is clicked or selected in Mission Control.


Steps to reproduce


  1. Enable Stage Manager.
  2. Open Safari and Phone.
  3. Arrange Safari and Phone together as one Stage Manager group.
  4. Click the desktop so the group moves into the Stage Manager sidebar.
  5. Enter Mission Control.
  6. Do not click or select any window.
  7. Exit Mission Control.
  8. Observe the Stage Manager sidebar.



Actual result

The Safari + Phone Stage Manager group has been dissolved. The applications are separated rather than remaining in their original group. In some cases, one application remains on the desktop while the grouping relationship is lost.


Expected result

Entering and exiting Mission Control without selecting anything should not modify or dissolve the existing Stage Manager group. The Safari + Phone group should remain intact.


Additional testing

The problem is application-dependent. Reproduced:


  • Phone + Safari → group dissolves
  • Phone + Finder → group dissolves
  • FaceTime + Safari → group dissolves
  • FaceTime + Finder → group dissolves
  • WeChat + Safari → group dissolves
  • WeChat + Finder → group dissolves
  • Microsoft Word + Safari → group dissolves
  • Microsoft PowerPoint + Safari → group dissolves
  • Telegram + Word → group dissolves
  • Telegram + PowerPoint → group dissolves


Not reproduced:

  • Safari + Finder → group remains intact
  • Safari + Notes → group remains intact
  • Safari + Excel → group remains intact
  • Safari + Telegram → group remains intact
  • WhatsApp + Telegram → group remains intact
  • Messages + Telegram → group remains intact
  • ExpressVPN + ChatGPT + System Settings → group remains intact



Single-app control:

  • Phone alone → survives Mission Control
  • WeChat alone → survives Mission Control


Therefore, the problem appears to involve the interaction between Mission Control and certain multi-application Stage Manager groups, rather than the individual application simply failing when Mission Control is opened.


Additional observations

The following Mission Control settings were disabled during testing:


  • Group windows by application
  • When switching to an application, switch to a Space with open windows for the application
  • Automatically rearrange Spaces


The system was restarted after changing these settings.


“Show windows from an application” was set to “All at Once.”


The issue remains reproducible.


The same Stage Manager workflow behaved correctly on macOS 26 before upgrading to macOS 27.


No external monitor is connected.


Frequency

Reproducible consistently with affected application combinations.


Expected behavior

Mission Control should be a non-destructive view/navigation mechanism. Entering and exiting Mission Control without selecting a window should not alter existing Stage Manager group membership or window arrangement.

Posted on Sep 18, 2026 12:55 PM

8 replies

neuroanatomist
User level: Level 9 (72,871 points)

Sep 18, 2026 1:10 PM in response to Aref Ha

Thorough description of testing and findings - well done. Particularly since you're seeing the issues with pairs of native macOS apps, this appears to be an Apple bug.


I'd suggest an additional set of tests, if you are willing. See if the problem is present when you boot in safe mode (no need to test everything, just a pair or two of native apps). Safe mode performs some system cleanup and clears caches, and also disables 3rd party extensions that may cause problems. Regarding Mission Control, there are a variety of issues with it being reported in Golden Gate and this may be related – other users reported that some of those issues did not occur in safe mode (because they were caused by conflicting extensions, presumably), thus the safe mode suggestion.

 

Start up your Mac in safe mode - Apple Support


If that does not correct the issue, test in a new user account. A newly-created user account will have all settings at default, and if the issue does not occur in that new account then it provides guidance on what may need to be changed to correct the issue.

 

Add a user or group on Mac - Apple Support

 

Once the testing is complete, the new account can easily be deleted.

 

Once done, bugs should be reported to Apple here (they won't read them in this forum):

Feedback - macOS - Apple


neuroanatomist
User level: Level 9 (72,871 points)

Sep 21, 2026 5:44 AM in response to Aref Ha

Aref Ha wrote:
For my workflow, the sate manager and grouping is vital and just don't know when Apple will repair such fundamental bug.

There have been many issues reported with Mission Control on macOS 27 Golden Gate. Some have been resolved by identifying and removing incompatible 3rd party extensions, others are bona fide bugs.


Reporting issues like this to Apple is the only way to get them fixed. They do prioritize bugs based on frequency of reports, so the more people who report it, the faster it will be addressed.

ityrdosp
User level: Level 1 (8 points)

Oct 10, 2026 12:58 AM in response to Aref Ha

Same here. macOS 27.0.1. It seems that some apps are not handled correctly by Mission Control in macOS 27, such as MS Word, WeChat, Phone.app. If they are in a stack, they get “kicked out” after MC is opened and exited, and other apps remain in the stack. It happens whether a stack is frontmost or not. But MS PowerPoint and Excel are not affected on my Mac; PP+Safari+Excel stack remains intact after MC. All MS apps are installed from Mac App Store. Reported to Apple Feedback.

gee-eff-ess
User level: Level 1 (90 points)

Oct 21, 2026 12:42 PM in response to Pro boy

Pro boy,


this is due to a Setting, that you've changed. Displays have separate Spaces, must be turned on for Stage Manager to work.


Aref Ha Author
User level: Level 1 (20 points)

Sep 18, 2026 8:12 PM in response to neuroanatomist

I tested both the "Safe Mode" and "A New User".

Nothing changed and the same malfunctioning was there.

For my workflow, the sate manager and grouping is vital and just don't know when Apple will repair such fundamental bug.

gee-eff-ess
User level: Level 1 (90 points)

Sep 21, 2026 5:36 AM in response to Aref Ha

I can confirm the behaviour.


I was really hopeful that this 'Snow Leaopard v2' macOS would solve the problems with Stage Manager and multiple Desktops, but it hasn't quite done that either. It's fixed them a bit, but it's not solid. I haven't gone through it fully yet, but basically, in macOS26, having Stage Manager on with multiple Desktops and using the App Switcher to move between apps in different Desktops and also using Mission Control, would quite quickly result in the app you switch to's windows all being inactive (none with red/yellow/green buttons). This appears to be fixed now, but in experimenting a little, I've found that an app with multiple windows can always have none active *plus* the Menu Bar slides up and out of sight. Very strange. Clicking one of the app's windows makes it reappear and all is normal, until you switch to another app, then back again and the windows are all inactive and the Menu Bar disappears ... even if they're both in the same Desktop.


(I run a totally 'plain-vanilla' OS. Zero utilities that alter OS behaviour).

marvelS51
User level: Level 1 (14 points)

Oct 15, 2026 10:03 AM in response to Aref Ha

I am also running into the same issue when I group unrelated apps in Stage Manager on one screen to have them displayed at the same time; after Mission Control is launched/closed, one of my grouped staged apps gets ungrouped.


I’m also seeing a second Mission Control issue: if I drag a window from one monitor to another in Mission Control, the monitor I dragged it from goes black. Swiping left or right with three fingers on that monitor brings the display back.

Pro boy
User level: Level 1 (8 points)

Oct 21, 2026 12:26 PM in response to Aref Ha

My Mac M3 has stoped working with stage manger the setting is grayed out. I wish I had not upgrade to ios27

Originally posted at discussions.apple.com/thread/256360005