I am using the Smart light app with a V2 Hub GE Zwave light switch and Smartthings motion sensor. Up until this morning, I would walk into the room and the lights would come on. Today, it is not happening. I checked and the motion sensor is seeing motion. Other smart light apps on timers are working.
I am at a loss. Any debugging tips?
Support can help you debug, they are great at this kind of stuff 
Many times just editing and resaving the app will fix things like this. Put in a ticket, then try some things people may post here, then notify support of resolution if you find it. That’s been my MO. Gives ST data, and if you are really stuck they are really helpful, and give the community an opportunity to help you up quickly and learn too.
Fixed by “editing” and saving the app.
Thanks!