In Windows 10, version 1803, the device name is no longer sent to the diagnostic data management service by default and requires a separate opt-in. The latest version of the deployment script enables this opt-in by default, but you can disable this behavior by setting DeviceNameOptIn = false. Note that the device name is also sent to AppInsights, so to ensure the device name is not sent to either place you would need to also set AppInsightsOptIn = false. Please be sure to enable this opt-in if you wish to continue to see device names in the admin portal for Windows 10, version 1803 devices. You can learn more about the deployment script here.
In addition, there was a slight change to the Connected User Experience and Diagnostic component endpoint URL for Windows 10, version 1803, so please be sure your network configuration allows access to this new end-point. You can learn more about the endpoint URLs here.