PreviewOneDrive
OneDrive: Sync support for up to 1 million items on macOS
OneDrive on macOS can now sync up to 1 million items in preview (currently limited to 300,000). Admins must verify device compatibility and enable Insiders ring access for testing; non-compliant devices remain at the 300,000-item limit with no disruption.
Action required: Enroll compatible macOS devices in the Insiders ring to test 1 million-item sync support; verify hardware and configuration requirements are met.
Microsoft's description
OneDrive Sync supports syncing up to 1 million items on macOS devices, helping teams manage large document libraries and shared content at scale without compromising access across devices. This preview requires the Insiders ring and that devices meet minimum hardware and configuration requirements. Devices that don't meet these requirements continue to sync at the existing 300,000-item supported limit with no disruption.