Firebase cloud messaging does not work after successfully sendToDevice

I use Firebase Cloud Functions for sending notification via Cloud Messaging to iOS device. sendToDevice method works great and returns success promise without any error or warning in Firebase Functions logs, but on iOS, notification is not showed. If I send notification from Firebase Notifications dashboard, it works great and notification is showed on the device. I don't know where I can have bug. It's possible that bug is on iOS app side, even when it works like I said?

Firebase configuration:

 var functions = require('firebase-functions');
 var admin = require('firebase-admin');
 var config = functions.config();
 admin.initializeApp(functions.config().firebase);

Part of cloud function:

APP.services.firebase.admin.database().ref('tokens/' + userId).once('value', function(snapshot) {

    var userDevicesTokens = [];

    snapshot.forEach(function(childSnapshot) {
        userDevicesTokens.push(childSnapshot.key)
    });

    if (userDevicesTokens.length === 0) {
        console.warn('No tokens for user');
        return;
    }

    var payload = {
        data: {
            title: options.title,
            text: options.text,
            type: options.type,
        }
    };
    APP.services.firebase.admin.messaging().sendToDevice(userDevicesTokens, payload)
        .then(function(response) {

            console.log("Successfully sent message:", response);

        })
        .catch(function(error) {
            console.log("Error sending message:", error);
        });

})

Firebase Cloud Functions log:

11: 52: 43.952 AM info newChatMessageTrigger
Successfully sent message: {
    results: [{
        messageId: '0:15016....'
    }],
    canonicalRegistrationTokenCount: 0,
    failureCount: 0,
    successCount: 1,
    multicastId: 589....
}

11: 52: 22.760 AM outlined_flag newChatMessageTrigger
Function execution took 604 ms, finished with status: 'ok'

11: 52: 22.252 AM outlined_flag newChatMessageTrigger
Billing account not configured.External network is not accessible and quotas are severely limited.Configure billing account to remove these restrictions

11: 52: 22.252 AM outlined_flag newChatMessageTrigger
Function execution started