Before anything, double check that you're using the correct version of the SmartThings app. The SmartThings Classic app is the one you want, not the newest SmartThings app. SmartThings is in the process of updating their platform and transitioning between the two apps. You'll need Classic to add the Power Switch correctly and get full functionality with SmartThings. The new app isn't complete and isn't fully compatible with most devices. So if you happen to be using the newer app, try downloading the SmartThings Classic app and including the device again.
If you're already using Classic, now it's time to try exclusion! Even if your Power Switch was never successfully added to SmartThings, exclusion is a kind of soft reset. It can helps with a variety of inclusion and configuration issues. Here's how to exclude the Power Switch from SmartThings:
1. Tap the menu icon in your SmartThings app
2. Tap Hub is online
3. Tap Z-Wave Utilities
4. Tap General Device Exclusion
5. The app will show this message: “Please follow the manufacturer’s instructions to remove the Z-Wave device from My SmartThings.” There will also be a spinning circle next to the message “Exclusion Mode Active”
6. On your Power Switch, press and release the Z-Wave button 3 TIMES QUICKLY
7. The app will confirm device exclusion
8. Tap Done
Once exclusion is completed, try including the Power Switch again by clicking on Add Thing in your SmartThings app and pressing and releasing the Z-Wave button 3 times quickly once again.
And if that still didn't solve the problem, here are some other things to try:
If you're still seeing issues with the switch after exclusion and re-inclusion, please let us know!