I would agree with you that it is a bug, ST didn’t agree with me when I reported it, I believe they logged my issue as a feature request. I’ve noticed the same thing - particularly with water valves. If you have a leak incident, fix what you thought was the issue, open the valve, but don’t actually dismiss the SHM event - subsequent leak events from any water sensor WILL NOT CLOSE THE WATER VALVE.
Seems crazy to me.