So, not to keep talking about Xbox in here, but this seems related:
-looks like notifications will be busted on Xbox one at launch.
Notifications are inconsistent and flaky for me on the other two MS systems based on the same underlying OS code: Windows 8.1 and Windows Phone 8. This can't be a coincidence. I think notifications are simply broken fundamentally on the platform. Sometimes they work, many times not. And they can be late, on time, or never show up at all. They seem to be a bit better on Win8.1, but I've noticed getting the same notifications twice, or late, and live tiles are just as unreliable on my PC as they can be on the phone. Not good news for the Xbox one as MS still hasn't ironed those out on platforms that have been out for a year now.