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

This is not a minor AutoSave inconvenience. It is a serious regression with a real risk of data loss and version conflicts.

We are now seeing this on multiple Macs in production.

The pattern is consistent:

• SharePoint document libraries are synced with OneDrive.
• A user opens an Excel or Word file normally from Finder.
• Office opens the file as “Saved to my Mac” instead of recognizing it as a SharePoint/OneDrive cloud document.
• AutoSave is disabled.
• Co-authoring and normal cloud-document awareness are effectively lost.
• Opening the same file through Office or SharePoint works correctly.

From the user’s perspective, nothing unusual has happened. They opened a SharePoint-synced file from Finder using a workflow that Microsoft has supported for years. There is no reasonable indication that Office has suddenly decided to treat that document as a local file.

That is exactly what makes this dangerous.

We already have several real-world cases of this behavior. A user can continue editing believing that SharePoint, AutoSave, co-authoring and version history are protecting their work, while Office has actually lost the cloud identity of the file.

This is not just a UI issue. It can lead to conflicting document versions, missed changes from other users and potentially lost work.

What makes the timing particularly concerning is Microsoft’s current rollout of the new OneDrive Native Sync Engine for macOS.

Microsoft explicitly states that the new engine changes the OneDrive and SharePoint integration with macOS and Finder. It introduces a redesigned sync architecture, changes how synced SharePoint libraries appear in Finder, and is intended to simplify the previous architecture.

I am not claiming that the Native Sync Engine has been proven to be the root cause. It has not. But given the timing and the exact point of failure, the relationship should be investigated properly rather than dismissed as an Office preference, cache issue, reinstall problem or user configuration issue.

The failure appears to be somewhere in the:

Finder → macOS File Provider → OneDrive → Office cloud-file identity handoff

The file may still exist inside the OneDrive sync location and may still synchronize at filesystem level, but Office no longer reliably recognizes that the Finder path represents a SharePoint/OneDrive cloud document. Office then treats it as a local file, displays “Saved to my Mac”, and disables AutoSave and cloud collaboration behavior.

This is also not an entirely unknown class of problem. Very similar Finder / “Saved to my Mac” / AutoSave failures have occurred with OneDrive for macOS before.

Therefore, “open the file from Office instead of Finder” is a temporary workaround, not a solution.

If Microsoft presents a SharePoint-synced Office document in Finder as a normal synced cloud file, then Office must reliably recognize its cloud identity when the user opens it.

Microsoft and Apple need to determine where the Finder / File Provider / OneDrive / Office handoff is failing and fix it.

Customers should not have to discover this problem through lost work or conflicting document versions.

For an enterprise collaboration platform, silently disabling the very mechanisms that are supposed to prevent data loss is not a cosmetic bug. It is a reliability failure.

And, somewhat ironically, when I tried to open a Microsoft support case for this issue this evening, the Microsoft 365 Admin Center itself was affected by an active Microsoft 365 service degradation.

Microsoft’s own Service Health notice states that administrators may experience authentication issues in the Microsoft 365 Admin Center, alongside impact to multiple Microsoft 365 services.

To be clear: the current Microsoft 365 outage is not the cause of this AutoSave problem. We observed the Finder/AutoSave issue before the current service incident started.

It simply means that, this evening, while trying to report a potentially data-loss-causing OneDrive/Office regression, the administrative support channel used to report it was itself degraded.

That is not exactly reassuring from a reliability perspective.