I am speaking for a friend, mostly because I want to figure out what might be causing this so I can help them figure out a fix for it.
They has played Fire Emblem: Awakening, and loves it- but lately there's been an issue where their save file deletes itself with no rhyme or reason.
They doesn't have anyone else that could be deleting it as far as I'm aware, and if it is a cause, they doesn't usually save mid-battle.
So- the question in question, is- what might be causing this?