iOS: files uploaded on one device are not visible on another device with the same iCloud account

[gromspys]

Describe the bug
On iOS, files written to iCloud on one device never become visible on another device signed in to
the same iCloud account. Each device only ever sees the files it uploaded itself, so data stored
from one device cannot be listed or read from another.

Steps to reproduce

1. Install the same build on two devices (iPhone and iPad) signed in to the same iCloud account
2. On the iPhone, run await CloudStorage.uploadFile('/from-iphone.zip', localUri, { mimeType: 'application/zip' })
3. On the iPad, run await CloudStorage.uploadFile('/from-ipad.zip', localUri, { mimeType: 'application/zip' })
4. On either device, run await CloudStorage.readdir('/') — only the file uploaded on that device
   is returned, and this does not change after hours of waiting
5. On the iPad, try to fetch the other file by its exact name:
   await CloudStorage.triggerSync('/from-iphone.zip') — fails with File not downloadable at path …

Expected behavior
Both devices list both files, and a file uploaded on one device can be downloaded and read on the
other.

Screenshots
Not applicable.

Environment:

• Device: iPhone 13 mini, iPad (10th gen)
• OS: iOS 26.4.2
• Library version: 3.1.0
• react-native: 0.83.4, Expo SDK 55, New Architecture
• Scope: CloudStorageScope.AppData

Additional context
The account and the container are the same on both devices: values written with CloudKVStorage
on one device are read on the other within seconds, and the container path reported in native
error messages is identical on both (…/Mobile Documents/<team>~com~<bundle>).
The directory listing on the receiving device does not contain .icloud placeholders for the
missing files either.