C# Pipeline.Invoke() not returning powershell collection

On Windows 10, in C# I am trying to call a powershell script via Pipeline.Invoke() to retrieve all the disks on a network server, for each server on a network. But can't get it to return the data to C# when there are multiple disks on a server.

I have the following C# code:
```
foreach (var server in _collServers)
{
  Pipeline pipeline2 = runspace.CreatePipeline();
  pipeline2 = runspace.CreatePipeline();
  scriptCommand = new Command(@"C:\DEV\Monitor\Monitor\bin\scripts\GetDisks.ps1");
  pipeline2.Commands.Add(scriptCommand);
  var collDisks = pipeline2.Invoke();

  foreach (var item in collDisks)
  {
    var s = item.ToString();
  }
}
```

which executes the following powershell script (GetDisks.ps1), with ComputerName hardcoded to a specific server for now:
```
$disks = Get-CimInstance -ClassName CIM_LogicalDisk -ComputerName SERVER01 | Where-Object {   ($_.DeviceID -ge 'C') -and ($_.DriveType -eq 3)} | Select-Object DeviceID, VolumeName, Size, Freespace

  $disksout = [System.Collections.Generic.List[PSObject]]::New()
  ForEach($d in $disks)
  {
    $disk = [PSObject] @{
      'DeviceID' = $d.DeviceID
      'VolumeName' = $d.VolumeName
      'Size' = $d.Size
      'Freespace' = $d.Freespace
    }
  $disksout.Add($disk)
}
$disksout
```
but it doesnt return a PSObjects collection into collDisks.

It works in the ISE (and every re-arrangement I try seems to work there).

It works if I run it for my local machine by removing -ComputerName SERVER01
```
$disks = Get-CimInstance -ClassName CIM_LogicalDisk | Where-Object { ($_.DeviceID -ge 'C') -and ($_.DriveType -eq 3)} | Select-Object DeviceID, VolumeName, Size, Freespace
```

It doesnt make any difference if I try using PSCustomObject instead, or creating the object collection different ways. I suspected its a type conversion issue, but using GetType() in various locations havent found the issue. Would appreciate if anyone else can cast light on the problem.