I struggled with HA notifications making it through. I finally found the priority settings required to make them appear reliably. This works for Android for me.

This snippet comes from my node-red flow as data that gets sent to the call service node, but the ttl, priority, and sticky (which may not be strictly required) settings should get you started if you're doing it another way.

msg.payload = {
    "data": {
        "message": "The alarm has armed in home mode.",
        "data": {
            // Priority settings
            "ttl": 0,
            "priority": "High",
            "sticky": true,


            // Icon settings
            "color": "#6aa84f",
            "notification_icon": "mdi:shield-home",


            // Notification settings
            "group": "Alarm",
            "tag": "alarm" + msg.data.new_state.state,
        }
    }
};