Last time I leave the game my was protected with 2 day shield, and before the 2 day someone can attack me even with my shield, how the he'll that can be possible !?
Please send us a message from the in-game Help option found in Extras and we will review our records of your shields. While we have seen some players mention this ins the past, we have not found a single case where a shield broke without the player performing an action.