Not receiving notifications on dual WhatsApp on Samsung Note8
I had problems with getting notifications for my dual Viber app and it seems that by default they are turned off.

So, you need to go to Notifications > Advanced and there you could find and manage your dual messenger's notifications.



I'm not sure that the path will be the same for your device but for the record I'm using Samsung Galaxy S7 with Android 8.0.0 on it.

Maybe that could help you with the issue.