This evening we left the house and armed the system to “stay.” When we returned, we opened and entered through the side door. We then opened the sliding door but never disarmed the system. I realized this when there was a flashing red light on the panel 20 minutes later. No alarm ever sounded. What did I do wrong?
It would appear that shortly before you left for the evening the side and patio doors were manually bypassed about an hour prior to arming. This would be why the sensors didn’t activate and trigger an alarm event.
You can login to Alarm.com and click on the history tab to see this chain of events as well.