Access denied msg when synchronising offline files

I have just purchased a new laptop for a user.  I have redirected their my documents folder to \\server01\users\sam and enabled offline files.  When I change a local file and attempt to synchronise the change back to the network I get the following msg:-

Offline files (\\server01\Users on server01): Access to 'filename.txt' is denied on \\server01\users\sam

I found this thread which seems to correspond to my problem, but after following the advice on there it still doesn't want to work:-
https://www.experts-exchange.com/questions/21724833/Offline-files-access-denied-error.html

My permissions look like this:-

User Folder (top level)
Share permissions:  everybody - full control
NTFS permissions: administrators - full control
                            domain users - modify

Sam's Folder
Not shared
NTFS permissions: administrators - full control
                            username - full control
                            owner - username

Any help much appreciated.

Thanks.