[Bug]: Mac OS VFS Client: "Enable Virtual Files" state resets when closing preferences window

[guilevi]

⚠️ Before submitting, please verify the following: ⚠️

• This is a bug, not a question or a configuration issue.
• This issue is not already reported on Github (I've searched it).
• Nextcloud Server and Desktop Client are up to date. See Server Maintenance and Release Schedule and Desktop Releases for supported versions.
• I agree to follow Nextcloud's Code of Conduct

Bug description

After checking "Enable Virtual Files" in the "Virtual File Sync" section of the client preferences, the UI becomes very slow (e.g. when tabbing around) and the checkbox resets as soon as I close the window and open it again. No Nextcloud entry appears in the sidebar unless I enable standard file sync, in which case the Nextcloud entry just points to the standard sync.

If I stay within the preferences window, the "Local Storage Use" section does not change at all (0.00/0.04GB).

I've tried enabling virtual files on fresh installations of the VFS client where I skip the standard sync step (I have to install Standard followed by VFS to avoid a segfault as referenced in #6730, which is closed but still occurs on my system), as well as on fresh installations where I go through the initial standard sync process.

Nothing significant seems to show up in Console logs, and the logs in Application Support only make references to standard-synced files.

Steps to reproduce

1. Install Nextcloud Standard client followed by VFS client
2. Add an account (adding a folder sync connection or not doesn't seem to matter on my system)
3. From the Nextcloud client UI, click on the current account and then settings
4. On the "Virtual File Sync" tab, click "Enable Virtual Files"
5. Tab around the UI
6. Close and reopen the preferences view

Expected behavior

Syncing of virtual files should begin when enabling the checkbox. The state should be remembered when closing and reopening the dialog.

Which files are affected by this bug

Nextcloud sidebar entry

Operating system

macOS

Which version of the operating system you are running.

Sonoma 14.5

Package

Official macOS 12+ universal pkg

Nextcloud Server version

Nextcloud Hub 8 (29.0.4)

Nextcloud Desktop Client version

Nextcloud-vfs-3.14.0-rc1-macOS-vfs

Is this bug present after an update or on a fresh install?

Fresh desktop client install

Are you using the Nextcloud Server Encryption module?

Encryption is Disabled

Are you using an external user-backend?

• Default internal user-backend
• LDAP/ Active Directory
• SSO - SAML
• Other

Nextcloud Server logs

No response

Additional info

While trying to reproduce this, I tried to specifically simulate a mouse click on the "Enable Virtual Files" checkbox (usually I'm activating it using VoiceOver) and this made my client crash. It now segfaults on startup. If I try to run the nextcloud binary from terminal, it shows the following:

Failed to initialize instances shared memory: "QSharedMemory::handle: doesn't exist"

This makes it impossible for me to create the debug archive. Sorry about this, please do let me know if there is any other way at all I can provide relevant logs!