Django_eventstream to send notifications from backend to frontend: the stream is established but it's empty

Question

I'm trying to send notification from backend (Django) to frontend (Vue.js) using django_eventstream

Following the library quide, I create endpoint in asgi.py:

import django_eventstream
import os

from channels.auth import AuthMiddlewareStack
from channels.routing import ProtocolTypeRouter, URLRouter

from django.core.asgi import get_asgi_application

django_asgi_app = get_asgi_application()
from django.urls import path, re_path

import sv.routing


os.environ.setdefault('DJANGO_SETTINGS_MODULE', 'project.settings')


application = ProtocolTypeRouter({
    "http": URLRouter([
        path(
            'frontend-notifications/',
            AuthMiddlewareStack(
                URLRouter(django_eventstream.routing.urlpatterns)
                ),
            {
                'channels': ['test'],
                }),
        re_path(r'', django_asgi_app),
    ]),
    "websocket":  URLRouter(sv.routing.websocket_urlpatterns),
})

At the frontend:

const es = new ReconnectingEventSource(url+ '/frontend-notifications/');
      es.addEventListener('success', function (e) {
            const data = JSON.parse(e.data);
            console.log('message', data);
        },            false          );

The event stream channel is established, it can be seen in the browser debug panel.

Then at the backend I send an event to the stream:

from django_eventstream import send_event

send_event(
            "test",
            "success",
            {
                "success": True
                }
            )

But there is no data in the stream.

I've tried to send data to the stream via requests as well:

import requests
session = requests.Session()
r = session.post(url, headers={'Connection': 'keep-alive', 'Content-Type': 'text/event-stream', 'Cache-Control': 'no-cache'}, data='data: Hello World\n\n', stream=True)

The request returns 200 OK, but again no any data in the stream.

How to send notification from back to front via SSE? Working example would be great.