[Bug]: macOS FileProvider/VFS - Folders with many files (1,500+) not updating

[aniqueta]

⚠️ 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

I have a folder where I dump my scans from a mobile phone app. That folder now has 1,500+ files. The server has no issues managing these files, and the web and iOS clients display the correct file counts and latest files. However, in Finder on macOS, when using FileProvider/VFS, the folder has stopped updating with new files, and it's missing 100+ of the latest files. On the iOS Files app, the folder times ~30 seconds to load, but all the files, including the latest, are present.

I also tested this by uninstalling Nextcloud macOS client completely and doing a fresh sync. It syncs correctly the first time, but eventually stops. (Not sure exactly when; right now, it's been out of sync for 2 months again.)

Steps to reproduce

1. Have a folder in Nextcloud with 1,500+ files
2. Add a new file to that folder from somewhere other than the macOS FileProvider/VFS client
3. Check the folder in Finder on the machine using the macOS FileProvider/VFS client
4. Note that the folder does not update with the most recent added file
5. Note that the Nextcloud client int he menubar thinks everything is up-to-date
6. Force a VFS sync in the Nextcloud menubar client
7. Again, note that the folder does not update with the most recent added file

Expected behavior

Same as above, but the folder does update appropriately.

Which files are affected by this bug

PDFs of scans from a mobile phone scanning app

Operating system

macOS

Which version of the operating system you are running.

macOS 15.7.3 (24G419)

Package

Official macOS Virtual files 12+ universal pkg

Nextcloud Server version

32.0.3

Nextcloud Desktop Client version

4.0.4

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

Additional info

I created a debug archive, but this is in a production environment, and there's just too much for me to review to remove sensitive information. Given I could reproduce this with a fresh install, I hope it can be reproduced for debugging in a test environment.

[hunter-nl]

I experience this bug also with folders with a few files. So many files in a folder is not related to this issue.
It won't sync any new files to desktop at all.
I only can get it working again, is to click on "Reset virtual files environment" button in the settings. But then it will do a complete "sync" of all the files again. And if you have many files then this will take a very long time. And this issue can reappear immediately after this full sync again.
MacOS 26.2
Nextcloud Desktop 4.0.4