Network folder is not synchronized between server and client

I have an issue with a folder on my server and on a client computer which are not synchronizing.  Both computers are desktops running Windows 7 Professional SP-1, and the LAN is a wired network using a Cisco router.   There is a folder within a TrueCrypt container, residing in a NAS which is connected to the LAN.  The TrueCrypt container is mounted, and appears as a physical drive V: in My Computer on the server.  The client computer has full access to network resources, and drive V:  is mapped as a network drive on the client.  The folder is visible on the client, and most, but not all, of the contents of that folder are visible.  Sometimes, when new files are added to that folder from the server, those files do not appear in the folder on the client.  Refreshing the view does not help, but if I add a new subfolder from the server side, then the new folder and the "missing" files immediately appear on the client side.  After that, newly-added files appear immediately in the client's view, until the issue reoccurs after some days.  To my understanding, the server and the client are exploring the same folder, so I'm baffled as to how there can be a disparity in the contents.