AutoSave disabled when opening SharePoint-synced files from Finder after macOS Tahoe 26.6 update

Hi,

Possible correlation found: OneDrive version pinned to old Sync Engine avoids the AutoSave issue

We've been affected by this exact issue (AutoSave disabled / "Saved to my Mac" when opening SharePoint-synced files from Finder) on a Mac running macOS Tahoe with a work/school account syncing SharePoint document libraries.

What we did:

- Used a script to pin/block OneDrive updates at version 25.243.1211.0001 (Standalone, Apple Silicon)

- Tested on macOS Tahoe 26.7

- Result: AutoSave works correctly and persists after a full restart

What we noticed in Finder that may explain why:

Our synced SharePoint libraries still appear grouped under a single root entry ("OneDrive - Shared Libraries - [org name]") in the Finder sidebar, rather than each library appearing as its own separate root.

According to Microsoft's Message Center post MC1458483 (OneDrive macOS Native Sync Engine, published Aug 21 2026), one of the explicit changes introduced by the new Native Sync Engine is:

"For users in organizations still using synced SharePoint libraries, this new sync engine now makes each synced library appear as its own root in the Finder sidebar, instead of nested under a single organization entry."

Since our libraries are still grouped (old behavior), this suggests our device has NOT yet been migrated to the Native Sync Engine, and that pinning the OneDrive app version may have prevented (or coincided with avoiding) that migration.

Hypothesis: the AutoSave/"Saved to my Mac" regression may be tied to the rollout of the Native Sync Engine on macOS Tahoe rather than to a specific OneDrive app build. This would explain why the bug has been reported across many different OneDrive versions (26.007.x, 26.055.x, 26.153.x, etc.) with no single "bad" build identified, and why some users report inconsistent results when just changing app versions.

Could anyone from Microsoft confirm:

1. Whether the Native Sync Engine rollout is tied to the OneDrive app version, the tenant, or the individual device/account?

2. Whether there's a way to check definitively if a given device has been migrated (e.g. a version suffix like "(26H)", or another indicator)?

3. Whether this AutoSave regression has been linked internally to the Native Sync Engine rollout?

Happy to share more diagnostic details (OneDrive About panel, Finder screenshots, fileproviderctl dump) if useful for triage.

Environment:

- macOS Tahoe 26.7

- OneDrive Standalone 25.243.1211.0001 (Apple Silicon), pinned via script

- Work/school account with synced SharePoint document libraries