azure-cli: Application Gateway - Error creating rule: Either all or no rule should have the priority specified

Related command az network application-gateway rule create

Describe the bug Attempting to create a new rule produces the following error:

ERROR: (ApplicationGatewayRequestRoutingRulePartialPriorityDefined) Either all or no rule should have the priority specified.

The CLI command does not provide the --priority flag so the priority number should be automatically generated (all other rules in the AGW have a priority already set).

To Reproduce Execute the following command:

az network application-gateway rule create `
        --gateway-name test-gateway-name `
        --name test-rule-name `
        --resource-group test-rg-name `
        --http-listener test-listener-name `
        --http-settings test-httpsetting-name `
        --address-pool test-address-pool-name

Expected behavior The priority value should be automatically generated by the service when it is not provided in the command.

Environment summary The CLI command is being executed by a ubuntu-18.04 Azure DevOps work agent.

Additional context This has only recently started failing (last couple of days).