I have had the same issue. Things it has been for me in the past
ST checking the Firmware
ST Updating the Firmware
The bulb freaking out because too much traffic relaying though it
Some thing on the Backend that ST had to fix. They never told me what. At first they said a user was doing it in the app. I explained EVERYONE was asleep at 3am. After a week and a half of silence, I got a message back that they found something in the back end and fixed it.