Get-WindowPosition -Window doesn't work with Variable but does if constant is used

Question

This one's got me completely stumped.

(New-Object -ComObject 'Shell.Application').Windows() | 
      ForEach-Object { 
        if ($_.locationName -contains "My Documents") {
             $pwnd = $_.HWND
        }
    }

$pwnd 

$Wnd = Get-WindowPosition -Window ($pwnd)

$SWPArgs = @{Window = $pwnd 
             Top    = 100 
             Left   = (($Wnd.Left)   + 100) 
             Width  = (($Wnd.Width)  - 100) 
             Height = (($Wnd.Height) - 100)
            }

Set-WindowPosition @SWPArgs
1246322
Get-WindowPosition : Cannot bind parameter 'Window'. Cannot convert the 
"1246322" value of type "System.Int64" to type "Huddled.Wasp.WindowHandle".
At line:10 char:35
+ $Wnd = Get-WindowPosition -Window ($pwnd)
+                                   ~~~~~~~
    + CategoryInfo          : InvalidArgument: (:) [Get-WindowPosition], Param 
   eterBindingException
    + FullyQualifiedErrorId : CannotConvertArgumentNoMessage,Huddled.Wasp.GetW 
   indowPositionCommand

You'll notice the value of the argument is: 1246322 If I manually type the value in on the command line it works!

PS> $wnd = Get-WindowPosition 1246322

PS> $wnd


Location : {X=1920,Y=0}
Size     : {Width=1862, Height=972}
X        : 1920
Y        : 0
Width    : 1862
Height   : 972
Left     : 1920
Top      : 0
Right    : 3782
Bottom   : 972
IsEmpty  : False

I've googled all over to try to figure out how to convert the Init64 to a Huddled.Wasp.WindowHandle without success. Ideas?

BTW: I've tried the argument value 3 ways: $pwnd | ($pwnd) | $($pwnd) all with the same results.