I'm gonna make this short and simple.
In this update, I discovered something horrible. Basically, when I join my own existing world (with Xbox account logged in), I was horrified to discover that my Multiplayer toggle is disabled when it should've been enabled by default when creating a new world.

How to replicate:
1. Start by logging in to Xbox account first.
2. Create a fresh, new world.
3. DO NOT tamper with the Multiplayer toggle when creating a new world.
4. Press "Create" to create a new world.
5. Press the pause button and look at the right side of the screen.

Expected results: The username below should have a "Invite to Game" button, so you can let friends join. Not only that, the Multiplayer tab in the Settings have the Multiplayer toggle enabled by default and cannot be toggled when in a world unless when editing that world.

What happened to me:
The complete opposite happened.