Steps to Remediate:
1. Verify read.all ( Both User.Read.All and Group.Read.All) are selected from the "Application Permissions" section and not the "Delegated Permissions" section. Choosing permissions from the "Delegated" section may prevent the Inspector from working correctly.
2. If your inspector is failing unexpectedly, check to see that "Microsoft.Network" is registered as a Resource Provider in your Azure subscription.
This setting can be checked by clicking Subscriptions > Resource Providers.