Thats weird, My one works completely fine. I get all notifications, whatsapp, email etc. some apps have a notification setting (in app) like whatsapp. You can change the setting there, maybe that may help. On my previous phone (Asus Zenfone 6) I updated to Lollipop and the notifications stopped, I couldn’t be bothered looking for a solution so I just factory data reset it and notifications started working again. However the first thing I did with my Meizu m2 Note was to update it to 4.5.3A, maybe its fixed in the latest version.