Windows 8.1 connected by VPN, contents of mapped drives "disappears" intermittently.

Question

I have a client with a Windows 8.1 Pro laptop who works in a satellite office and connects to the main office via VPN. The main office is running SBS 2011.  The user has his G drive mapped to a share on the server and will be working on 2 or 3 files,
he'll then go to open the G drive to find another file and he'll see that only the files/folders he's actually been working on are showing up, the rest of the contents of the drive seems to "disappear".  I believe this is caused by the VPN dropping
connection (not proven yet).  The problem is that even if you reconnect to the VPN, those files don't re-appear... or they might be back when he comes back into the office after doing some calls.  We can make the files instantaneously re-appear if
he grabs his notebook, walks across the street from the satellite office to the main office and plugs into the hardwired network... but this is less than practical, and impossible if he's actually on the road somewhere.
He does not have "offline files" active for the G drive, nor do we really want to do that... but I'm thinking that Windows is going into some sort of half-baked automatic offline files mode when the VPN goes away.   I've played with
registry and group policy settings in reference to offline files in the hope that would rectify the issue but to no avail.
We don't particularly care that the files are unavailable when the VPN isn't connected, the client understands they aren't local files.  What is really the big issue is that activating the VPN doesn't make the files reappear and that there doesn't seem
to be any consistent way of "forcing" the issue except to physically hardware to the lan segment the server is on.
This was working just fine on the client's old system under Windows 7 Pro, but just since moving to a new laptop with Windows 8.1 it has become flakey.
Any suggestions hints or tips are appreciated.
Cheers,
Mike
P.S. When I say the files "disappear", they are just invisible to this user... they are still physically on the server and accessible by all other users on the LAN. 

Answer 1

I will have to double check again to make sure I'm telling the truth (I've gone through so many iterations in the past weeks I can't remember which way is up :-)  but I believe that the drive was showing in offline files, but that attempting sync (even
repeatedly) did not bring the drive contents back.  Which also begs the question, if the user has not made the drive "available offline" why would it be acting like it is?  I've considered actually making it available offline, but I don't want
all of that data on his laptop and I'm also concerned that we'd then have more problems as he continues to work for hours and days on his offline copies.
I should also add that I was able to work with the client on Friday and we were able to determine that the VPN is NOT dropping as we're able to ping devices on the LAN side immediately once the files disappear.  
Cheers,
Mike