This is still happening for me. My partner just paid to open a realm and we uploaded a copy of the world there, only to find that now, it crashes for both her and myself, which is different to previously where the bug only affected myself.
This happened to me about one week ago, I died in the nether a few times due to Blazes and then Minecraft completely crashed. Since then I am unable to enter that world, either on Realms or downloaded locally.
In this state Realms is unusable, because resetting the world isn't an option due to how much effort has been put into the current world.
When attempting to join the world the client makes nether sounds and then crashes.
Windows 10 Edition, v1.0.0.
Still crashing when logging in to Realm, on version 1.0.5.