Mouse specifically not working

The KBD and Mouse will now work Natively wired or wireless

Previously you needed an adapter.

Games that use KBD and Mouse are Developer specific

If a device is not specifically labled as working with Xbox, it will not. In the case of a keyboard/mouse, only basic features are supported. An Xbox is not a PC

I think the specifics of the question aren't about using mouse and keyboard, but rather if you can use a keyboard and mouse that operate via a wireless dongle.

That is, plug dongle into Xbox, then mouse and keyboard comme t to dongle, wirelessly.

I'm not sure that this works, though.

Upon looking at support site, which specifically states WIRED USB keyboard and mouse, so I'm unsure

EDIT: , there may in fact be models supported by console that are wireless, but not just any wireless keyboard will function so check first

If you have one that you would like to try, go for it, just note that mouse and keyboards will not work with all games. As it's still a new feature some products may not work as intended, so I advice caution if you intent to purchase a wireless mouse specifically
for your Xbox.

It might be an issue with the mouse being wireless.
The specific page for Mouse and Keyboard support denote specifically using a wired mouse, so that might be worth checking out.

But for this issue, I'd have to recommend you to reporting it as a
Bug to Mojang, as they are the ones who would have to fix it within the game application. Microsoft does own them, but they are the development team who would have to do the work to fix it. And Microsoft does support Keyboard and Mouse for the system
and in games, but they only control how it works at the OS level navigation and use, and not how it is implemented in games, as that is up to a design choice in the game for the developers.