This Home app solved our little disaster; heres the story:
We paid a bunch of money for Lutron "Caséta Wireless" dimmers and a Smart Hub with the HomeKit option. You can imagine our disappointment when we discovered the Lutron app does not support activating Scenes using Siri (HomeKit), which for us was the whole point of smart lighting. You want to be able to say "Siri, its movie night." For $15, this Home app fixed the problem. After all the money we had spent, $15 is cheap, especially when it solves everything.
Note that the Lutron app is still necessary for pairing your devices. And it does have "scenes," but for some reason they are not connected to HomeKit, even though the individual devices are!
And this app fixes a problem with iOS 9.3.1 which made our kitchen lighting stop responding. Our On/Off Lutron switches decided they were "switches" and not "lights," so they stopped responding to things like "Turn off all the Kitchen lights." I was able to tell each switch that it was really a light, and voila! This level of control wasnt available in the Lutron app.