This just started happening today. I'm on AT&T but running the official OS 7.1.0.342 from Telenor Norway (vendor xml's have been deleted). I'm not sure if it's an OS issue; I've been running 7.1.0.342 since it was officially released...what was that? A few weeks ago or so? The only changes I've made to my phone were deleting the Photobucket app and BBM Music yesterday. I have reset twice and still getting the issue. The icon flashes so I know it's picking up that it's on the charger. Besides, I was at 47% when I put it on the charger and got up to 94%, so it can't be an issue with the connection. I have reset twice and still getting the issue. Any ideas?
To add to Homer1475's comment; you should do a couple of battery pulls and plug the charger in between these. This could help resetting the battery meter.