I am unable to upload any world, newly created or existing, to my Realm. I have tried this on existing and a new realm. I get Export in Progress, Initializing Upload and then, after a period of time, the famous "An error occurred" Message.  It appears I an unable to put existing worlds I have no newly created worlds there. 

I tried the same from my XBox and there it works fine so I suspect it is an iOS issue. I have restarted my device also with no luck.