I HAVE SAME PROBLEM ... uninstalled the game 60 times, reset my iphone 6 two times, changed internet connections, DID EVERY POSSIBLE THING. According TO my faction members who can view my stats, my lvl went from 68 - 143... My cash went from 3 mil -> 333mil. WTF?
This is also the case with a few other members in my faction. All of them experience a lvl growth.