owncloud client does not sync (always unresponsive) on windows

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Describe the bug

Client just becomes unresponsive and does not sync

Expected behavior

Sync

Steps to reproduce the issue

No response

Screenshots

No response

Logs

log is flooded with 10000+ lines of similar to below

26-06-06 11:10:03:035 [ warning sync.vfs.win ]:	void __cdecl OCC::VfsWin::fileStatusChanged(const class QString &,class OCC::SyncFileStatus) : couldn't CfSetInSyncState for "C:/Users/Public/Apps/LMStudio/locales/bg.pak"  status  OCC::SyncFileStatus::StatusNone : "WindowsError: -7ff8fe88: The file is not a cloud file."
26-06-06 11:10:03:036 [ warning sync.vfs.win ]:	void __cdecl OCC::VfsWin::fileStatusChanged(const class QString &,class OCC::SyncFileStatus) : couldn't CfSetInSyncState for "C:/Users/Public/Apps/CLion/plugins/clion-radler/DotFiles/ExternalAnnotations/.NETFramework/System.Deployment"  status  OCC::SyncFileStatus::StatusNone : "WindowsError: -7ff8fe88: The file is not a cloud file."
26-06-06 11:10:03:036 [ warning sync.vfs.win ]:	void __cdecl OCC::VfsWin::fileStatusChanged(const class QString &,class OCC::SyncFileStatus) : couldn't CfSetInSyncState for "C:/Users/Public/Apps/CLion/plugins/clion-radler/dotCommon/DotFiles/JetBrains.Profiler.Windows.RemoteAgent.xml"  status  OCC::SyncFileStatus::StatusNone : "WindowsError: -7ff8fe88: The file is not a cloud file."
26-06-06 11:10:03:037 [ warning sync.vfs.win ]:	void __cdecl OCC::VfsWin::fileStatusChanged(const class QString &,class OCC::SyncFileStatus) : couldn't CfSetInSyncState for "C:/Users/Public/Apps/CLion/bin/mingw/x86_64-w64-mingw32/lib/libiiscfg.a"  status  OCC::SyncFileStatus::StatusNone : "WindowsError: -7ff8fe88: The file is not a cloud file."
26-06-06 11:10:03:038 [ warning sync.vfs.win ]:	void __cdecl OCC::VfsWin::fileStatusChanged(const class QString &,class OCC::SyncFileStatus) : couldn't CfSetInSyncState for "C:/Users/Public/Apps/FreeCAD/bin/Lib/site-packages/scipy/special/_orthogonal.py"  status  OCC::SyncFileStatus::StatusNone : "WindowsError: -7ff8fe88: The file is not a cloud file."
26-06-06 11:10:03:039 [ warning sync.vfs.win ]:	void __cdecl OCC::VfsWin::fileStatusChanged(const class QString &,class OCC::SyncFileStatus) : couldn't CfSetInSyncState for "C:/Users/Public/Apps/CLion/plugins/python-ce/helpers/typeshed/stdlib/builtins.pyi"  status  OCC::SyncFileStatus::StatusNone : "WindowsError: -7ff8fe88: The file is not a cloud file."
26-06-06 11:10:03:040 [ warning sync.vfs.win ]:	void __cdecl OCC::VfsWin::fileStatusChanged(const class QString &,class OCC::SyncFileStatus) : couldn't CfSetInSyncState for "C:/Users/Public/Apps/CLion/bin/cmake/wsl/x64/share/cmake-4.1/Help/manual/cmake-qt.7.rst"  status  OCC::SyncFileStatus::StatusNone : "WindowsError: -7ff8fe88: The file is not a cloud file."
26-06-06 11:10:03:041 [ warning sync.vfs.win ]:	void __cdecl OCC::VfsWin::fileStatusChanged(const class QString &,class OCC::SyncFileStatus) : couldn't CfSetInSyncState for "C:/Users/Public/Apps/CLion/plugins/python-ce/helpers/typeshed/stubs/docutils/docutils/transforms"  status  OCC::SyncFileStatus::StatusNone : "WindowsError: -7ff8fe88: The file is not a cloud file."

Client version number

ownCloud 6.0.3.18040 7c8209 Libraries Qt 6.8.3, OpenSSL 3.4.3 30 Sep 2025 Using virtual files plugin: wincfapi OS: windows-10.0.26100 (build arch: x86_64, CPU arch: x86_64) QPA: windows ownCloud

Desktop environment (Linux only)

No response

Client package version and origin (Linux only)

No response

Installation path (Windows only)

c:\Program Files\ownCloud\

Server information

Infinite Scale 8.0.1 Community ownCloud Web UI 12.3.2
on docker using owncloud/ocis image
data is on mounted NFS disk (100 mbit/s)

Additional context

No response

Start at the VfsWin::fileStatusChanged entry point shown in the logs and investigate the Windows virtual-files path in the listed ownCloud 6.0.3.18040 environment. Reproduce the sync stall with the wincfapi plugin and determine why CfSetInSyncState returns “The file is not a cloud file”; done means syncing remains responsive without the repeated warning flood.