BEST ANSWER:

Had this problem as well. After doing research I learned that the Z-Wave network is route based. I have several Z-Wave devices. In this topology you cannot pair the device right next to the hub and then move it somewhere else because the route to get to it would need to change. So basically, when you physically move it, the controller no longer knows how to find it. Since my bulbs are quite a ways from the controller, I ended up buying a repeater and then paired them in their installed location (one is about 30 feet away) and everything works great. Note: I believe in order to get them to pair, I also had to force the Smartthings hub to re-optimize its routes (a couple of times). Can't remember for sure if that was before or after pairing.