Wow! I thought I was only one of a rare few suffering in silence from this problem! Haven't checked back here in awhile.
Yeap, same issue as y'all. M1 Galaxy Note 2. Have been experiencing this since December 2012.
After a short while of inactivity, Whatsapp does NOT prompt for any new messages AT ALL. Even booting the phone from sleep doesn't show a damn thing. Only after going into the CHAT itself will new messages come up (this means that even just going into the chat list shows nothing).
This happens even in areas with good network connectivity. Tried emailing the Whatsapp team, they threw all the usual bull**** at me (reinstall app, reboot phone, etc.). Obviously none of that worked. They finally gave up, asked me to send a log, and never got back to me.
Strangely, the girlfriend's phone is perfectly fine. M1 Galaxy Note 2, too. So I'm always on the receiving end of a scolding whenever she waits an hour for my reply
So who does the fault lie with? M1/Samsung/Whatsapp?