I don’t have one of these yet, but that message could be related to a few things, including hub problems.
Before going too far, try power cycling the device. I assume this is behind a wall plate? If so, trip the breaker it’s connected to and see what happens. It may take a minute or two to “wake up”.
If that doesn’t work, go to the device’s preferences (the little gear in the upper right corner) and tap on Replace. If a message comes up saying something like “ready to replace device…”, power cycle the device. If that works right, you’ll eventually see a message like “successfully replaced…”. If the message “checking device…” just sits there, the device and ST think they’re talking to each other, and something else is up.
You’ll have to log on to the IDE and start going through device and hub event logs at some point if the things I mentioned above don’t help. If you’ve not done that before, a call/email to support may have to be done.
Are any of your other devices doing that? Also, maybe a reboot of your hub will work.