Notifications are working for me now with the beta version. I removed whatsapp completely, reinstalled from the App Store. Then it worked again, notifications coming though but with the "ff, fi" bug.. Then i installed the beta signed with my own certificate over the app store version and the push notifications are still coming trough!
Guys I went trough for some situations that you describe here. I kept in touch with an italian friend that explained to me some details about Whatsapp and its beta process.
First, in order to push notifications work properly in iOS 8 beta 2 with Whatsapp beta you have to disable iCloud chat backup. Inside app, go to chat setting and set chat backup to none. Then you'll have notifications back.
Second, It's very hard to find (have googled extensively with no luck) an updated ipa. Who published .828 ipa file claims that works in iOS 8 beta 2 without problems, and in my experience was totally a mess. It freezes constantly and iPhone heats up quickly with high battery consumption of course. What I think, is not true that it works well, because Whatsapp beta 2.11.9.828 was released before iOS 8 beta launch on WWDC so it makes no sense at all.
But there's a few links in the internet that connect to Whatsapp beta source that updates to current beta version instantly but when you install it on your iPhone it downloads over 2.11.8 (current in app store) but it says can't install, that try later. Of course with no provisioning profile and certificate it doesn't work neither.
So, said that, I purchased a developer certificate that works on Zeusmos and InstaSign. Question is, there is no place to find a Whatsapp beta 2.11.9.XXXX ipa file up to date to try it on. With dev certificate and the latest WA beta IPA it's possible to have best of both worlds, iOS 8 beta and a WA working properly.
Have any of you found a beta IPA file later than 2.11.9.828?