Issue #
There are various sync issues when syncing Microsoft 365 Sharepoint Online files and Onedrive for Business (ODFB) files with a local workstation via the Onedrive or Onedrive for Business client.

Solutions #
The following steps can be taken to troubleshoot and resolve any Onedrive for Business sync issues:
- Check on the Windows taskbar area for Onedrive specific errors or warnings and research the error in the Microsoft community to find a resolution action.
- Ensure that the error you are facing is not due to an inherent limitation of Sharepoint Online or Onedrive for Business. Consult this article for a full list of by-design limitations and restrictions: https://support.microsoft.com/en-gb/office/restrictions-and-limitations-in-onedrive-and-sharepoint-64883a5d-228e-48f5-b3d2-eb39e07630fa.
- When using an external disk drive with ODFB, ensure that the target disk drive on which OneDrive for Business syncs its data is formatted with the NTFS file system. Other file systems are not supported. Review the following KB article for further instructions: https://support.microsoft.com/en-us/office/install-onedrive-on-an-external-drive-6307e24b-d7a4-493f-bf43-47345b2c11fe.
- Run the Microsoft guided online troubleshooting wizard available at: https://support.microsoft.com/en-us/help/10104/troubleshooting-onedrive-for-business-sync-issues
- Check the Windows event logs for any Onedrive specific error or warning.
- Check the OneDrive for Business event logs under C:\Program Files\OneDrive and under %localappdata%\Microsoft\OneDrive.
- Clear the ODFB cache files by removing below folders:
- Check the status of your Internet connection (network RTT, latency, dropped packets)
- Check any third party antimalware programs or Windows security programs (Controlled folder access, Defender, etc) which may interfere with OneDrive for Business.
- Right click the local folder with files creating issues and tick the "always keep on this device" option in order to force the offline sync of the contents of this folder.
- Reset the ODFB client as per https://support.microsoft.com/en-us/office/reset-onedrive-34701e00-bf7b-42db-b960-84905399050c.
- Uninstall and re-install the Onedrive for Business sync client. The latest version can be downloaded from https://support.microsoft.com/en-us/office/onedrive-release-notes-845dcf18-f921-435e-bf28-4e24b95e5fc0?ui=en-us&rs=en-us&ad=us
- Run the Microsoft Support and Recovery Assistant, available for download at: https://support.microsoft.com/en-us/office/about-the-microsoft-support-and-recovery-assistant-e90bb691-c2a7-4697-a94f-88836856c72f
- Create a new Windows local profile and perform a clean installation of Onedrive for Business in that new Windows profile.
- If all else fails, open a support ticket with Microsoft using your licensed Microsoft 365 product. In case Onedrive log files are needed, the location of the Onedrive logs is %LocalAppData%\Microsoft\OneDrive\logs.