OneDrive on Mac: files visible but won’t open, folder backup/copy fails after years without syncing

Yes. The behavior described is consistent with known OneDrive for Mac issues around Files On-Demand, moved OneDrive paths on macOS, and sync state problems.

Most relevant points for this scenario:

1. On macOS 12.1 and later, OneDrive uses a new Files On-Demand location: Library > Cloud Storage > OneDrive If files are being opened from old pinned/recent references or the old folder path, they may appear present but fail to open correctly until accessed from the new OneDrive location.
2. If AutoSave or file access is tied to the old path, Office and Finder behaviors can be inconsistent until files are opened from the new OneDrive folder location.
3. If OneDrive shows sync problems or stale local state, Microsoft’s supported recovery path is:
   • Unlink the Mac from OneDrive: OneDrive menu bar icon > Help & Settings > Preferences > Account > Unlink this Mac
   • Clear cached sign-in credentials in Keychain Access by searching for OneDrive and deleting OneDrive Cached Credential
   • Open OneDrive again from Spotlight and sign in
   • When prompted that the folder already exists, select Use this folder
4. If sync is stuck or inconsistent, update to the latest OneDrive version first. Microsoft also notes that resetting OneDrive can resolve sync issues, but it disconnects all existing sync connections and then performs a full sync afterward. No files or data are lost by resetting, but it is still a disruptive step because all sync relationships are re-established.
5. For Desktop and Documents backup on macOS, OneDrive requires:
   • the standalone sync app, not the Mac App Store version
   • Full Disk Access for OneDrive in System Preferences > Security & Privacy Preferences > Privacy
6. If apps hang when opening or saving files stored in OneDrive on macOS 15, Microsoft lists a workaround using Activity Monitor to force quit OpenAndSavePanelService, then restarting OneDrive and saving or moving the file to another folder location.

For the safest supported path to get to a complete backup-capable state:

1. Update OneDrive to the latest version.
2. Open Finder and verify the actual OneDrive location under Library > Cloud Storage > OneDrive.
3. Try opening files from that location rather than old aliases, pinned items, or Recents.
4. If the folder still behaves inconsistently, unlink and re-link the OneDrive account, and when prompted choose Use this folder.
5. If Desktop/Documents backup or copy-related access is involved, confirm the standalone sync app is installed and Full Disk Access is enabled.
6. If sync remains stuck, use the documented OneDrive reset process.

Risk note: deleting .DS_Store files with Terminal is documented as a possible fix for sync problems caused by corrupted .DS_Store files, but it requires administrator access and use of sudo and rm -f. That should be used carefully and only for the affected folder, because deleting the wrong item in Terminal can cause unintended loss.

• Missing files and autosave issues with OneDrive on macOS
• Fix OneDrive sync problems on Mac
• Fixes or workarounds for recent issues in OneDrive
• Back up your folders with OneDrive
• Remove DS_Store Files on macOS