Tim,
Is this failing consistently or randomly? I saw that one of your previous posts indicated that other volumes are found but it seems that just this volume fails. If you run the Get-NaVol with no name switch, does the volume return? I wonder if there is any difference in the state,options,or configuration of that volume than the others. I am curious if you saw this post from a few months ago in another part of the communities. The OP in the PowerShell Toolkit forum was having a very similar problem. The suggestion was to try the -Terse option.
https://communities.netapp.com/message/94955#94955
Jeremy Goodrum, NetApp
The Pirate
Twitter: @virtpirate
Blog: www.virtpirate.com