Hey guys,
I had some issues with my tiles not updating on my 7 Pro (running WP7.8, but I guess the not updating issue is the same on WP8 and WP7.8). A few days ago my Amazing Weather Tile stopped updating. I tried some other apps (Fuse, Das Image) and realised: none of them updated their tiles. At least not as often as they should... I rebooted my phone, checked all the background apps (only the ones I used for the live tiles were activated) and so on... nothing could solve my problem.
After a day or two I deleted WhatsApp from my phone. (I really don't like WhatsApp and the idea of being "online" all the time. My friends tend to think that just because of a smartphone having an internet connection the user is available all the time. I use SMS and email a lot, so I don't need WhatsApp so much... Because of not really having the "need" to use WhatsApp AND the really annoying Song-Playing-For-WiFi-issue I deleted the app)
After doing that my phone started to update all the tiles! There was just one day (a period of maybe 4 hours) where there were no updates. I gues it was because of some connection issues from my provider. As I said: the tiles work just fine now!
Don't know weather or not WhatsApp was the main problem, but my phone works just fine after deleting it... Maybe you should give it a try?