Just to make sure everybody’s talking about the same thing…This FAQ is for people using both the V2 classic app and the 2018 V3 app.
The security feature in the classic app is SHM, Smart Home Monitor.
The security feature in the new V3 app is STHM, SmartThings Home Monitor.
These are two completely separate pieces of code.
Security mode set or changed (or an alert dismissed) in an automation created in the classic app will only affect SHM. .
Security mode set or changed (or an alert dismissed) in an automation created in the new V3 app will only affect STHM.
So if you have rules you created in the classic app, you will never see those change the security state in the new V3 app. You have to recreate the rule using the new V3 app to see security mode changes in the V3 app.