Editing XML content with PowerShell working locally but not via Invoke-Command

Question

I'm trying to script the removal of a XML node using PowerShell from a .xml file on a remote computer.

My Invoke-Command scriptblock is:

$remoteResult = Invoke-Command -ComputerName myserver.com -ScriptBlock {
    Param($FolderName) 

    $xmlFilePath = "c:\foo\Folders.xml"
    $localLog="c:\foo\removefolder.txt"

    [XML]$XMLContent = Get-Content $xmlFilePath -Encoding UTF8
    Write-Output $FolderName | Out-File $localLog -Append
    Write-Output "Entering loop" | Out-File $localLog -Append
    foreach ($Folder in $XMLContent.Folders) {
        $XMLFolderName = $Folder.SelectSingleNode("//Name[.='$FolderName']")
        Write-Output "Folder = $folder" | Out-String | Out-File $localLog -Append
        Write-Output "XMLUserName = $XMLFolderName" | Out-File $localLog -Append
        if ($XMLFolderName.'#text' -eq $FolderName) {
            $XMLUserName.'#text' | Out-File $localLog -Append
            Write-Output "User entry found for $FolderName, removing." | Out-File $localLog -Append
            $XMLFolderName.ParentNode.ParentNode.RemoveChild($XMLFolderName.ParentNode)
        }
        Write-Output "Folder entry not found?" | Out-File $localLog -Append
    }
    Write-Output "End loop" | Out-File $localLog -Append
    $XMLContent.Save($xmlFilePath)
} -ArgumentList $remfolder *>&1

I've added a load of Out-File statements to generate a log on the remote machine to see what the state of things are during the script execution. I can see the $FolderName is being passed correctly, then I get:

Entering loop
Folder = System.Xml.XmlElement

XMLUserName =
User entry not found?
End loop

If I get it to Out-File the Get-Content line it successfully reads the file and saves it to the log, so the .xml file is being read successfully.

If I copy the above code to the remote server and run it directly from there without the Invoke-Command statement, and manually pass the value of $FolderName, it works fine and removes the XML node as expected.

So I'm not sure what is happening differently when it's run remotely.

Edit: As requested, here's an example of the XML format being accessed.

<?xml version="1.0"?>
<Folders>
  <Folder>
    <Name>Folder1</Name>
    <Location>\\server.com\share$\folder\Folder1</Location>
    <Limitations />
    <Description>Folder One</Description>
    <CustomField />
    <UserPermissions />
    <GroupPermissions>
      <Permission>
        <IdentityName>Folder One</IdentityName>
        <ListRestriction>
          <Type>Deny</Type>
          <Extensions />
        </ListRestriction>
      </Permission>
    </GroupPermissions>
  </Folder>
  <Folder>
    <Name>Folder2</Name>
    <Location>\\server.com\share$\folder\Folder2</Location>
    <Limitations />
    <Description>Folder Two</Description>
    <CustomField />
    <UserPermissions>
      <Permission>
        <IdentityName>Folder Two</IdentityName>
        <ListRestriction>
          <Type>Deny</Type>
          <Extensions />
        </ListRestriction>
      </Permission>
    </UserPermissions>
    <GroupPermissions />
  </Folder>

So for instance in the script I'm assigning $FolderName as "Folder2". When run locally it successfully removed that entire Folder node, remotely it doesn't.