Using applescript with Calendar in El Capitan

I've been trying for weeks to script an ipad restore process for Apple Configurator 2. My script works fine when ran within Script Editor, and it also works as a stand alone application. The problem occurs when my script is launched from a Calendar event (which is the whole idea so I don't have to run it manually). Here is the first part of my script:

tell application "Apple Configurator 2"
activate
delay 30
tell application "System Events"
    tell process "Apple Configurator 2"
        keystroke "a" using {command down}
        delay 5
        click menu item "1 - Erase" of menu 1 of menu item "Apply" of menu 1 of menu bar item "Actions" of menu bar 1
        delay 5
        click button "Apply" of sheet 1 of window "All Devices"
    end tell
end tell

The script triggers just fine, and all is working until it attempts to click the "Apply" button. My script application returns this error:
Can't get window "All Devices" of <> "Apple Configurator 2" of application
"System Events".

System Events got an error: Can't get window "All
Devices" of process "Apple Configurator 2". (-1728)

As an Applescript newbie, I'm out of ideas. Anybody else?
Thanks!