Previous versions not available on file server share. But vss seems to be working
Solution 1:
We have several servers running VSS and had two instances where VSS just stopped working, and it was due to a snapshot gone wrong.
I would turn off VSS, format the partition, and turn it back on, and you will probably find it will work fine again.
Solution 2:
A little late to the party, but thought I'd add this in case it helps anyone.
Make sure TCP/IP Netbios Helper service is running. This enabled me to see the previous versions on the server.