I would guess that there will be a problem with permeability - like how contact lens are made to allow oxygen to reach the eyes so cells don't die. I am thinking that there will be no way for the egg to get the oxygen it needs, or moisture - or loose moisture as it grows.
When you put it in the bag you lost the natural air cell that the egg had. Not sure how exactly you would replace this or how long it can go without the oxygen.