If you're using the Apple TV 4 check the following:
1. Go to---> Settings/Accounts/iCloud
2. Make sure that under your iCloud account you see that Homekit is "Connected".
After the iOS 10 release if you don't have your house connected, the App loses the identities of the doors after a day or two. This happened to me. I had to log out and log back in. A few minutes after logging back in my house appeared as connected. Haven't had any issues since.
Other than this, I'm really happy with the Sense locks. I have HomeKit unlock all my doors at night automatically at 9pm so I'm never lying in bed wondering if I locked the doors.
Thanks, mine says connected, but I wonder if my issue is if my internet goes down the the Apple TV doesn't reconnect automatically when the internet comes back up.
I'll have to do some testing and see if this is my issue.
PS: I think you meant at 9pm HomeKit locks the door. Not unlock.