I have no problem so far on notification. It always notify
me when I am on standby mode and even display a short message on my
home page when I switch on. Got to go through the various
areas to find out where it got "switch off". I use Andriod
phone
1. Making sure the Whatsapp is not connected to the Whatsapp web
but directly from Wifi network; if you are not sure,
reinstall the Whatsapp from play store;
2. in App Manager, find Whatsapp app, check if the
notification check is on
3. In the notifcation under setting, make sure one
has the correct setting and turn on notification sound.
4. Make sure the group or name of the Whatsapp
person has not been muted or set not the display notification.