I don't receive Viber notifications on Nokia 6

[AC Question]

Hello, I installed Viber on Nokia 6 and I don't see any notifications about new incoming messages. Only after I manually open the application, I can see if any new messages were sent. I tried Settings -> Notifications -> Viber and I see that everything looks fine, "Block all" is disabled, "Show silently" is disabled... then "On the lock screen" is set to Show all notification content... also, settings in Viber application look good. So, what is the problem??? Anyone can help?