Question about close-nccifssession and maybe a bug

I am getting sporadic wierd results with get-nccifssession and piping it to close-nccifssession.  


Half of the time, it works fine, and I checked close-nccifsession and it acceptions pipeline input from sessionID, but the other half of the time, I'm getting errors 



TerminatingError(Close-NcCifsSession): "Parameter 'SessionId' is mandatory for Data ONTAP 9.0 and up."
close-nccifssession : Parameter 'SessionId' is mandatory for Data ONTAP 9.0 and up.
At C:script.ps1:925 char:62
+ ... {$_.windowsuser -match $user} | close-nccifssession -confirm:$false
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ CategoryInfo : InvalidArgument: (svm1:NcController) [Close-NcCifsSession], ArgumentException
+ FullyQualifiedErrorId : SessionIdRequired,DataONTAP.C.PowerShell.SDK.Cmdlets.Cifs.CloseNcCifsSession


Anyone else seeing this? 


I'm using 4.3.