iCloud Drive on Windows repeatedly initializes and doesn't sync new changes

Hello,

Apple Support suggested that I post this issue here because they were unable to identify a server-side problem. According to Support, the iCloud service is operating normally, so the issue may be specific to my Windows PC or to iCloud for Windows.

I would appreciate any advice from users who have encountered similar behavior, especially anyone familiar with the Windows Cloud Files integration used by iCloud Drive.

System

• Windows 11 Professional 25H2, build 26200.9457
• iCloud for Windows 15.10.0.39
• iCloud Drive component 3.12.11.6
• Advanced Data Protection is enabled
• MacBook, iPhone and iCloud.com are also connected to the same Apple Account

The problem

iCloud Drive on Windows repeatedly enters a long “Initializing items” / updating state.

The initialization may involve tens of thousands of items and can continue for a very long time. After restarting iCloud for Windows or restarting the PC, the client may begin a large initialization process again.

My working dataset is relatively large — approximately:

• 63,000 files
• 6,500 folders
• around 70,000 filesystem objects in total

However, the most important problem is not simply the duration of the initial scan.

New changes that already exist in iCloud sometimes do not appear in Windows File Explorer while iCloud for Windows is initializing.

I performed the following reproducible test:

1. I closed iCloud for Windows.
2. On my MacBook, I created a new folder in iCloud Drive.
3. I started iCloud for Windows.
4. The first folder appeared in Windows almost immediately, and iCloud for Windows then started “Initializing items”.
5. While that initialization was running, I created two additional empty folders inside the same iCloud Drive folder on the Mac.
6. I immediately opened iCloud.com in a browser on the Windows PC.
7. Both new folders were already visible on iCloud.com, confirming that the Mac had successfully uploaded the changes to iCloud.
8. However, those folders still did not appear in iCloud Drive in Windows File Explorer. Windows continued to show the folder as empty.

This seems to isolate the issue:

Mac → iCloud → iCloud.com works correctly

but

iCloud → iCloud for Windows → File Explorer does not reliably receive/apply the new changes.

The Mac does not appear to be the problem because the changes are visible on iCloud.com almost immediately.

Errors found in the iCloud for Windows logs

I found several recurring or notable errors:

0x80073D0F

Couldn't connection to notification center

0x80070178: The file is not a cloud file

0x800706BF

Failed to create ISyncNotifyIcon

and:

NetworkStatus::NetworkConnectionDidChange Online (false) != connected (true)

There was also an occasional:

Instance already running. Exiting.

Troubleshooting already performed

• iCloud for Windows was repaired and later completely uninstalled/reinstalled.
• The problem returned after reinstalling.
• Windows Cloud Files driver CldFlt is running normally.
• Controlled Folder Access is disabled.
• WinHTTP proxy is not configured.
• Windows user proxy is disabled.
• iCloud.com works normally.
• iCloud Drive on the Mac works.
• iCloud on the iPhone works.
• I tested networking with and without different VPN routing configurations, including full-tunnel VPN, without resolving the iCloud for Windows behavior.

Apple Support has told me that they are not currently seeing a known iCloud service-side issue affecting my account and suggested that the problem is probably on the Windows device.

My questions

1. Has anyone seen iCloud for Windows repeatedly perform very large “Initializing items” operations like this?
2. Is it normal for iCloud for Windows to delay or stop processing new remote iCloud Drive changes while the initialization process is running?
3. Does anyone recognize errors 0x80073D0F, 0x80070178 or 0x800706BF in connection with iCloud Drive / Windows Cloud Files?
4. Could this indicate a corrupted or inconsistent iCloud Drive SyncRoot, Cloud Files placeholder database, local iCloud metadata database, COM/AppX registration, or notification/event subscription?
5. Is there an Apple-supported way to completely rebuild the local iCloud Drive state on Windows without deleting any data stored in iCloud?
6. Is approximately 70,000 files/folders considered a supported workload for iCloud for Windows, or are there known practical limitations when the number of objects becomes large?
7. Would it be reasonable to upload the initial dataset through macOS instead, allow the Mac to complete the upload to iCloud, and then let the Windows client reconstruct its local iCloud Drive view from the cloud?

I do not want to manually delete registry entries, SyncRoot registrations, Cloud Files databases or other system components without knowing that the procedure is safe and supported, because these are important working files.

I can provide additional iCloudDrive/iCloudHome log excerpts if anyone knows which entries would be useful.

Any advice from someone who has dealt with iCloud for Windows at the Cloud Files / SyncRoot level would be greatly appreciated.