I haven't been able to find a solution since September. Well one was to restart 2 times and that would work. But had a user yesterday couldn't access the drive even after reboot 3 times. I couldn't even disconnect the drive explorer would hang. Even tried net use to delete the drive nothing.
So since I could browse the path I added to quick access and she was able to access it that way, while the mapped drive to same location still didn't work.
Then I stopped Workstation service as you said, then started it. Instantly I was able to access all the shared drives including the already mapped drives to nas. Then I restarted 4 times and at no time did I lose access. It's so strange that restarting the PC didn't have the same affect as stopping this services and starting it up. It must clear something when stopped.