Thank you for reaching out!
Were you in the middle of a live view session when the incident took place? For the moment, Alfred’s Motion Detection does not function during live view sessions.
Also, if your Smart Motion Detection is on, Alfred would prompt you to switch Motion Detection off when your devices share the same network. You might have accidentally switched Motion Detection off that way.
Please read more about Motion Detection and notifications here:
Hope this helps! Please let me know if it works!