I have just updated Zombie Annihilation. It was really tiny change, just changed some variable value so I've published it to Google Play production stright away.
My friend have updated the game (on Xperia Z1 mini) and everything looked alright. He was already on 51st wave (pretty deep in the game) and managed to get to wave 53. Then he turned off the game.
When he ran the game again all saved data was lost. He got wave 1, no cash, no weapon etc... everything what was in LocalStorage - gone.
Now the funny part. I have updated game on my SGS4 and everything is fine. No data has been lost. Restarted game many times and it's ok.
And even funnier now. He removed the game and installed it again. Now everytime he turns off the game everything is gone.
Is it possible that LocalStorage behave differently on various devices? I hope it's a problem with his mobile only, but in other hand he didn't have this problem with earlier version.