The above device, and several other wifi based plugs (mostly Kasa) all function as originally intended and are obviously online, yet Hubitat has shown this red not-connected icon on them ever since the new UI changes were implemented.
I haven't seen it brought up yet so I figured I would mention it.
That shows up if there's a comms error (check the device attributes). In Preferences, turn off "Kasa Cloud Binding" and it should disappear. And the Comms error attribute will change from true to false.