Fairly regularly I will get an audible alert that I have a new email and will then go and check my phone, and the notification area will be empty. If I actually go to my laptop, or open the phone's email client I will see that I do have new emails, but no sign of them in the notifications. This is inconsistent and most of the time notifications are there as expected, but I've seen this maybe a half dozen times in the last week or two. A separate issue I have is many times notifications will pop back up again and again in the notification center even after I've cleared them. Things like missed calls and text messages will occasionally show up days after I originally cleared them.