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

You’ve isolated this to the Finder launch path: the same SharePoint files retain cloud identity and AutoSave when opened through Office or SharePoint, but Finder hands them to Office as local files after the Tahoe update. Microsoft’s AutoSave guidance says files opened from Finder may need reopening from within Word, Excel, or PowerPoint, so “Saved to my Mac” does not indicate a SharePoint permission or sync failure. Use Open > Sites or SharePoint’s Open in Desktop App as the workaround; avoid Finder for collaborative editing while it reports a local location. Capture the macOS build, Office build, OneDrive version, affected library, and reproducible test file. Send feedback from the Office app and open a Microsoft 365 admin support case with those details and timestamps. Since reset, relink, Keychain cleanup, and File Provider checks made no difference, further local resets are unlikely to help; Microsoft needs to investigate the Finder-to-Office handoff.