I am using the oppo f1s 3gb 32gb in Pakistan. I recently update my mobile to Marshmallow from lollipop 5.1. Now the problem is that i receive notifications but but their notification icon did not shown on status bar.
Here i confirmed from Official customer care office of oppo mobiles that recent update of marshmallow in oppo f1s have this issue . and can't be resolved in marshmallow. They suggest me to downgrade your phone back to lolipop 5.1 to remove this issue. So i personally suggest that don't update your oppo f1s to mashmallow .
First, make sure whatsapp notifications are on. Go into WhatsApp settings, notifications, and make sure all notifications are on.
There are a few possibilities as to why whatsapp shows that you received a message, but there was no notification.
First, if you have muted a contact or a group, and deselected "show notifications" then WhatsApp will still show that number on the app icon, but no notification will come.
Anther reason could be, that you simply cleared notifications. In that case the number on the app icon will still stay