Clicking on 'Manage Offline Files' does nothing in the Sync Center
Solution 1:
Check if you have the Windows 10 Home by clicking on start then click on setting. Select System. Then select About down at the bottom left. There it will show if the Windows 10 Home is installed or the Windows 10 Pro.
If you have the Windows 10 Home, then you will not have access to the offline file managing just like the Windows 7 Home does not have access to this feature.