Grouping of multiple notification not working

[ukrolelo]

Greetings,
can somebody advise why its not working to group multiple notification from my django-webpush?
I tested homeassistant html5 notify and my phone is able to group/replace a notification, how can i do it with django-webpush?
timestamp = datetime.datetime.now().strftime('%Y-%m-%d %H:%M:%S')
payload = {
"head": "CLOUD",
"body": "Changes on N%s, click here" % stpnum,
"icon": "/static/dist/img/logo.png",
"badge": "/static/dist/img/logo.png",
"url": "/home/%s/" % cpuid,
"data": {"tag": "renotify","renotify": True},
"tag": "renotify",
"default": True,
"renotify": True,
"timestamp": timestamp,
}
send_user_notification(user=user, payload=payload, ttl=1000)