A few things to try:
- Make sure you're using the latest version of the
Update-Module -Name Az.Blueprint
- Make sure your Azure subscription context is accurate:
Set-AzContext -SubscriptionName "mySubscription"
- Verify your role-based access control (RBAC) permissions at the desired scope(s)
Also, please note that Azure Blueprints is gradually being replaced by Azure Resource Manager (ARM) template specs and deployment stacks. Just FYI.
Thanks a lot,