ComputersNeedingThisUpdate always shows 0 in UpdateServices PowerShell module

I've just written an extremely simple script to query our WSUS server to check how many servers need a patch that has been approved. Here's the code:

$patchID = "KB2992611"
$wsusServerName = "wsusserver"
$wsusserver = Get-WsusServer $wsusServerName -PortNumber 8530

# Get approved patches that are still needed:
$approvedandneeded = Get-WsusUpdate -UpdateServer $wsusserver -Status Needed -Approval Approved

# Filter to get the patch you're after:
$filteredUpdates = $approvedandneeded | Select-Object -ExpandProperty Update | Where-Object { $_.Title -match $patchID }

foreach($update in $filteredUpdates)
{
	$updateDetails = Get-WsusUpdate -UpdateId $($update.UpdateID) -UpdateServer $server
	Write-Output "Computers needing this update: $($updateDetails.ComputersNeedingThisUpdate) | $($update.Title)"
}

Output

Computers needing this update: 0 | Security Update for Windows Server 2008 R2 x64 Edition (KB2992611)
Computers needing this update: 0 | Security Update for Windows Server 2012 R2 (KB2992611)
Computers needing this update: 0 | Security Update for Windows Server 2008 x64 Edition (KB2992611)
Computers needing this update: 0 | Security Update for Windows Server 2008 (KB2992611)
Computers needing this update: 0 | Security Update for Windows Server 2003 (KB2992611)

As you can see, the ComputersNeedingThisUpdate attribute/property is always showing 0. This is despite the WSUS console showing completely different results. I *know* most computers need that patch and I can see this through the console, just not via a script.

It's worth stating that the ComputersInstalledOrNotApplicable and ComputersWithNoStatus properties return accurate data, it's not a problem with the code.

Help is appreciated.

Regards,

Robin