This is not really a PowerShell Code errors / functionality issue, but how do I find and match up my AzureRM resources and extract information.
However, since you are here...
If the property is not there, then you are not looking at the correct resource cmdlet / object. I don't have this type of scenario deployed in my sub, so no way to dig at it. Take a look at this
Workspaces - Get
URI Parameters Name In Required Type Description
subscriptionId path True string Gets subscription credentials
which uniquely identify Microsoft Azure subscription. The subscription
ID forms part of the URI for every service call. resourceGroupName
path True string The resource group name of the workspace.
workspaceName path True string Name of the Log Analytics
Workspace. api-version query True string Client Api Version.
And use the provided properties to cross reference, specifically the resourceGroupName and or workspaceName.