Xbox Minecraft split screen isn't loading

I have been building a survival world with my brother and his friends for months. Everything has worked fine before this summer, but for the past few months it has not been working. ( I am on split screen with my brother, the Minecraft world is actually his world ) Minecraft does this thing where it says building terrain and the bar is up for hours but I still can't load in. It is stressing me out so much so hopefully you can do something about it. Thank you.