Persistent Missed call notification frequently re-appears. How to remove it? Somebody called me sometime before but I missed the call. Then I called back and everything was ok but whenever my phone connects to the WiFi i.e. when I go to different places; I see the same missed call notification frequently. I also cleared the cache and also cleared the Viber data but it frequently reappears. Its been more than 2 days. 

How can I solve this issue?
I got a solution today. The notification was of a contact whose chat was 'hidden' in another device (PC) or same device before phone was factory reset or something. 

Go to Settings -> Privacy -> Hidden Chats
Since I don't use this feature, I tapped the 'Reset PIN' which deletes all existing hidden chats. That's it. That useless notification is gone. 

I am surprised that no answer was posted for so long.
I was facing this problem since February and I came across this post several times as it shows up at the first page of Google search.