I would suggest you to try out all the below troubleshooting steps.
Work Folders syncs files between client and server. Although most issues are discovered by users, it could be root caused on the server, the client or the network. This blog post shares the most common problems customers have reported, and some troubleshooting techniques on Windows devices.
There are also good Technet articles on Work Folders here:
https://technet.microsoft.com/en-us/library/dn265974.aspx
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