Hi Guys I've have been having the same problem, missed calls not showing.
I've managed to fix the problem although it took some time and I found it by accident.
1. Go to settings and scroll down to Google.
2. Open Google.
3. Hit the 3 dots in the top right corner.
4. Hit clear app data.
5. A box will open asking!
(You are about to delete all third-party app data stored within your Google account)
I confirmed the OK command and my missed call icon showed in the status bar after I received a call.
I hope this works for you guys.
PS I'm well chuffed it's the 1st thing I've ever figured out on any phone and I've owned mobile phone 15 years lol
I want to try this as I am facing the same problem but I am afraid it will set the phone t factory mode and have all the data on my phone deleted. Does that happen or it has no effect on the data?
Thank you for the post. Finally, after a couple of weeks of not having notifications I have them again. Tried so many other options but this works like a charm, great job Mavs086!