On my system when setting the Smart Home Monitor from the Dashboard to Armed(Away), Armed(home) or Disarmed it seems that the related SH Routines in Automation do not execute, nor can I find a way to set this. This causes the Mode to become mismatched/disassociated with the Alarm State creating failures in any Apps or Pistons that rely on the Mode setting.
Am I missing something or is this how SmartThings functions?
It sounds like you may be confused about the difference between smart home monitor armed status and “mode.” That’s a common issue.
Read the following FAQ (this is a clickable link) and see if it clears up the confusion:
You should be changing the mode and that should Arm/DisArm your location.
You can use routines to change the mode and SHM and other things. Using the SHM on the dashboard will only change the SHM status. You can add the routines in the favorites on the dashboard for easy access.
It works fine when I tap on an automation routine and only use automation routines.
However, if I tap on Goodbye in the automation routines, then go to the Dashboard and tap Disarmed, the IDE Location shows
Alarm System Status: Disarmed
Current Mode: Away
Is this what occurs on your system?
You should be Changing the Mode and having it DisArm.
The Mode “Away” is not connected in any fashion to the Smart Home Monitor Armed Status “Armed Away”-- you have to set up something, most commonly a routine, to change one if the other one changes. You can also use webcore for this. But you have to have a rule that ties them together.
Again, see the FAQ to understand the difference between these two variables. 
This kind of sums it up, but to me it feels like the ST app is rather Schizophrenic or suffering from cognitive dissonance.