My niece with the microsoft account named ClaireJellyFish has been trying to download a few different items from the in game store and they just get stuck at 0.0mb. She has plenty of room on her tablet.  I have cleared the games cache and the in-game stores cache, rebooted the tablet, and reloaded and tried again a few times and it still gets stuck.  One is an add-on pack called MORPH Add-on and another is called Pyramid Base.