Yes, I'm still having issues. I've tried restarting my console, restarting my router, and using a smaller world. It didn't fail, but a freshly created world was loaded instead of the one I selected.
I'm gonna send you up to our Realms team! I would try a couple more times of uploading the World though. To keep your information secure, please complete our request form at aka.ms/Minecraft-Support so we can quickly and safely assist with your question! ^TK