Unable to Replace World for Realm

I have been trying to replace my world with another world but am unable to do so. Everytime I try, it exports showing 0mb, then it initializes, then it loads up to 100% and stays there indefinitely. I have tried to wait it out and left it on for around 8 hours but to no avail. The world is just around 117mb. Sometimes when I retry, it automatically fails.