Get-AzureVMDscExtensionStatus does not work when using a VM object

Repro

1. create a VM and set the DSC extension on the VM
2. $vm = get-azurevm -ServiceName ServiceName -Name VmName
3. Get-AzureVMDscExtensionStatus -vm $vm

Expected

Give you the status of DSC on the specified VM or an error indicating the DSC extension is not on the VM

Actual

returns nothing