Though native support is there now - the instructions are not clear.
Make sure the device is in pairing mode. There are no instructions in the Sylvania quick start. Neither is not listed in the list of devices supported in the IDE or the app.
All you have to do is,
Add a thing in Smart and keep it in discovery mode.
Unplug the Smart+ pluug, when you are plugging back again - hold the power button now
Then it would show up in the app!
Hope it helps someone!