I’ve fixed it – it is due to Security SmartApp putting hub in zombie state.
I’ve had an issue with clearing up notification then even stop sending SMS/notification and at this point ST is useless. I’ve had restarted hub, hit clear notification individually and none of trick worked.
Finally, I took route to removing all smartApp which is associated with devices ( painful route ) and then clean up. Dashboard got GREEN and then installed Security SmartApp on open/close sensor and bingo … SMS/notification started and also now clear up intrusion detection notification the way it was. So, follow the same and you will have all clear up.