If I add new sensors/zones to the Vista 20P with Surety/Alarm.com, will Alarm.com detect them and they will be added the mobile app, etc? Or do I need to force Alarm.com to rescan the panel?
If you add a sensor to your Vista 20P panel, It should automatically pick it up and add it to alarm.com. In the case that it doesn’t, power cycling the panel should cause the panel to perform the panel sync in which it scans the whole panel for all panel programming and sensor programmed into it.
To perform a power cycle, unplug the transformer that provides the panel power first, then disconnect the backup battery. Wait a few seconds then connect the battery first followed by the transformer. The scan should take about 20 minutes. Do not touch the keypad during this time.