I don't have the same problem, I have an older Synology NAS that has two ports in a LACP group which is tagged as "Synology" when I go to Network-Wide > Alerts under x goes down for more than x minutes I can see the Synology tag.
One thing that is limiting with this alert is you can only choose one tag so if you need to monitor a variety of devices via this alert you will need to have common tag for them to use.