Are you using any custom functionality in your modes? (custom modes/rules, schedule, geofencing, etc.) If so, does the same behavior occur when using the default, "Armed" mode?
I've not been able to replicate any issues receiving push notifications. If you're still experiencing this issue, I recommend contacting the Arlo Support Team to further investigate this issue. You will find several options for contacting support in the provided link.
Con of HomeKit: only sends “motion” notifications when you are home and doesn’t classify any movement other than “motion”. I even set up emails when arlo smart fails again when I’m away from home.
Also the following week of arlo not sending push notifications it’s mysteriously fixed itself but I will not be trusting of arlos push notifications as this has happened twice now and I’ve only had arlo for a month...
Conclusion: don’t fully trust arlo smart but when this thing works I do love it. But not reliable. Must use HomeKit as well and receive double the alerts.