Mac Studio desktop assignments revert to None on OS27

There have been many issues reported with Mission Control and Spaces on macOS 27 Golden Gate, especially regarding assigning apps to Desktops, and the way Full Screen apps and app switching are handled. Some have been resolved by identifying and removing incompatible 3rd party extensions, others are bona fide bugs. The minor point update, macOS 27.0.1, did not appear to address the more significant issues.

Bugs should be reported to Apple here:

Feedback - macOS - Apple

See if the problem is present when you boot in safe mode. That process performs some system cleanup and clears caches, and also disables 3rd party extensions that may cause problems.

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.

Delete a user or group on Mac – Apple Support

Those steps will help to isolate the problem.

It might help to download and run EtreCheck, written by a long-time forum member. The free version is fine. Post the full report using the Additional Text button. No personal information is revealed. 

If the issue persists in safe mode and a new user account, that suggests that it's a bug that Apple needs to address. 

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.

Personally, Mission Control is working fine for my use cases on my 16" M4 Pro MBP running 27.0.1. I have many Spaces and open windows, but I don't assign apps to Desktops or use full screen apps and I don't have my apps grouped, all of which are associated with reported issues.

If you have automatic updates in for macOS, then that may be why it’s fixed. This bug was addressed in the macOS 27.2 update.

It has taken me a while to find time to return to this issue. Today, I set up a bunch of desktop assignments for apps so I could shut down and boot up my Mac in safe mode to see if they held. Before I got that far, I noticed that the assignments seemed to be sticking, and they're also saying "Desktop X on Display Y", which wasn't the case before. These assignments have now persisted through opening and closing apps, launching apps by opening a file from the Finder and restarting my Mac.

I have recently been spring cleaning my Mac Studio, trying to address another issue – when I restarted my Mac Studio a couple of weeks ago, it booted up as though it had just been through a software update (Welcome screen appeared, settings were back to their defaults). I'd experienced this occasionally with my old Mac Pro, and I wondered whether Migration Assistant brought over something that was causing the same problem on the new machine. I spent a fair bit of time disabling start-up items and removing old Intel software (including some 32-bit stuff I had never deleted). This appears to have fixed the restart issue, and maybe it also fixed the desktop assignment issue as a bonus. Keeping fingers crossed for now.

I, too, have this issue. I have 6 virtual desktops and I have assigned various apps to those desktops. Once made, the assignments stick around for several days. I also have Mission Control keyboard shortcuts assigned (^1 thru ^6 as well as ^left arrow and ^right arrow). Then inexplicably, ^2 thru ^6 stop working, however ^1 and ^left and right arrows work. System Settings shows that all of these shortcuts are still assigned.

Once I reboot, the keyboard shortcuts work just fine. But then most (but not all) app desktop assignments return to "none". I must then reassign the apps to their respective desktops. Then the assignments as well as keyboard shortcuts work as they should - for several days - until the shortcuts fail again and I must reboot and restart the process of reassigning app desktop assignments.

Thanks for the reply neuroanatomist – a very helpful set of suggestions. I’ll work my way through them and report back.

Nope, I'm still on v27.0.1. Time to update!