Many Windows Phone 8.1 users have been reporting that OneDrive, OneNote and Office apps are not syncing. The users have been facing the Syncing issues for their Windows Phone 8.1 devices since last week and are not able to update any files or folders to OneDrive or OneNote.
The syncing issues seems to be effecting only the Windows Phone 8.1 users and the users on Windows 10 Mobile are not yet facing the issues. The company currently has closed the Upgrade path for users who roll back to Windows Phone 8.1 will not be able to update their devices back to Windows 10 Mobile.