1. Clear all IE browsing history.
2. Stop syncing all SkyDrive Pro folders (move away current folders to avoid duplicate renamed folders) for the client in question.
3. Close all your Office processes, such as groove.exe which is OneDrive,msouc.exe, msosync.exe, office library sync via Task manager.
4. Browse to "C:\Users\username\AppData\Local\Microsoft\Office\Spw" and delete all the content. You will find that this is all related to groove, and spw equals SharePoint Workspace.
5. Go to "C:\Users\username\AppData\Local\Microsoft\Office\15.0\OfficeFileCache" and also delete all content of this folder. This is where all the cache of your files are stored.(it's ok if one or two items cannot be deleted).
6. After completing the above mentioned steps, please start OneDrive Pro via using "Program Files\Microsoft Office\Office15\GROOVE.EXE" or type "groove" in the Search programs and files filed in Start, then launch the groove).
7. Re-sync your library.