Realm replacement issue. Initializing upload forever and then tell you there was a error

Put the summary of the bug you're having here

What I expected to happen was...:
To download old realm and upload it to new realm

What actually happened was...:
Download of realm was successful but when uploading it to my new realm plus it gets to initializing upload and doesn't show my upload progress and says it for a very long time before message says an error occurred 

Steps to Reproduce:
1. Put a step by step guide on how to trigger the bug here
2. ... go to settings on a  none realm world that you've been playing.
3. ...click play on realm

Or

1) Go to edit setting on realm.

2) click replace world

3) select a world you've played on and want to play on a realm now