How does Lutron react when there is a power cut?

Your lights will go out unless you have a backup generator. The important thing is what happens when the power returns. Your system will go back to it’s previous state. If you were having a dinner party, it goes back that setting. If all the lights are off as it’s the middle of the night, they remain off. Your system will remember it’s state, and all of the programming for 10 years without power.