notifications not sending in browser

Description:

No notification pops up in browser when new messages. When first enterring Rocket Chat, it ask for permision to send me notifications. I never see / receive none.
The messages are sent / received correctly by all users in the room, but you have to visit the room in order to see if there are new messages.
The javascript Iframe listener detects the activity ( althought it detects it 3 times, instead of only once, strange behavior. We have a point system and want to award users for being active in chat, receiving a triplicated message in javascript its a problem for us )
Notifications fail in Iframe and directly in server url.

Steps to reproduce:

1. Enter any room
2. Send any type of message
3. The rest of the room participants should be notificated about new message, but no notification is sent to users.

Expected behavior:

Send / Receive notifications about new messages and activity in lobby as advertised in https://rocket.chat
Easy way to keep track of activity in several Rooms.
**Image from https://rocket.chat

Actual behavior:

Nothing changes regardles of new messages, users in room, ... ( and besides sometimes rooms are duplicated -> issue: 13715 )

Server Setup Information:

Version of Rocket.Chat Server: 0.74.2
Operating System: Linux x64, Ubuntu 18.04
Deployment Method: snap
Number of Running Instances: 1
DB Replicaset Oplog: Info not available in Rocket Chat Info (or badly translated to Spanish), so maybe it could be added in the future.
NodeJS Version: v8.11.4
MongoDB Version: Info not available in Rocket Chat Info (or badly translated to Spanish), so maybe it could be added in the future.

Additional context

Seems that the sidebar is buged.

Relevant logs:

No relevant error log.

Start by reproducing the issue in a browser using the listed steps, both in an iframe and at the direct server URL, with Rocket.Chat 0.74.2. Inspect the browser notification and sidebar behavior, including the reported triplicated iframe activity and the related issue 13715. Done means new-message notifications appear reliably without duplicate activity events or duplicated rooms.