I have the same problem I cannot Even replace my world with a downloaded backup...
There's nothing wrong with my internet connection. I just tested it. There is nothing wrong with it. It works fine on other apps.
This happens with a complete reinstall of Minecraft, in addition. I have tried that. I've also asked My other realm member to try it and they have the same issue and same versions as I have. This happens in survival.
I have downloaded the world and tried it in creative as well as survival with the same issue.
I am planning on bedrock. Yes I've tried shutting it down and making sure it's closed in the apps screen. It has the same issue.