You’re on the right track. Try exiting the ST app completely and try discovery again. Give it a good 30 seconds or so to detect the device. You also may try removing and re-plugging the power on the device to reboot it once.
There’s a weird bug in SmartThings that we haven’t really been able to 100% account for on this discovery screen that I think you’re running into.
Also, open up the Live Logging tab in the ST IDE for some debugging info. Email us at help@konnected.io if you still have trouble.
It will eventually work!