If you hit issues using the Gallery runbooks (like StopAzureV2Vm seen below), you may need to add a value to the environment name.  Just like when connecting to Azure Government via Azure PowerShell or CLI, you need to specify the environment name.

Add the value per the screenshot below and you should be fine!

previously posted on https://blogs.msdn.microsoft.com/nicole_welch/2018/02/azure-automation-using-sample-runbooks-in-azure-government/