What appeared to work for me:
Click the + to add a new device in ST
Pull the battery tab on the Sylvania Motion sensor
It’s discovered as a “thing”
Log into the IDE and change the handler to Smartsense Motion Sensor and save.
remove battery from motion sensor
Click the + to rediscover new devices
Put battery back into motion sensor
verify in the ide that you see temp and batt data from the device
click X to cancel discover devices on your phone. It won’t have found anything, but somehow this makes the device work fully, rather than being stuck in the motion on, and no temp or batt data state.
This sensor has a nice build quality. Very similar in appearance to the Iris/Centralite one from Lowes, but a little sturdier.