Why does the standalone Xbox program keep telling me I need Xbox Game Bar just for voice chat?

This is not about the forums. It's the voice chat. When I tried to join voice chat in Game Bar, it closes. When I tried to join voice chat from my Xbox App mobile, it reveals an error.

Try opening your Xbox menu by pressing the home button on your controller, then clicking "audio". There should be a volume bar for game vs voice chat below the regular audio bar. Moving this bar to the right makes the game louder and voice chat quieter,
moving it to the left makes voice chat louder and the game quieter. Hope this helps!

Forgot to add almost everyone i game with are in the prievew program, though some are not.

This does not effect the part chat working for me or voice messages sent to me.

This is driving me crazy. I've now spoken made a support thread to XBox, who tell me I need to talk to Neflix.

Netflix tell me they do not support voice support, and any voice functions are provided by Xbox themselves so I need to talk to XBox.

Why on earth am I getting a totally different experience to everyone else?

Hi,

So you can start a Voice Chat with another player, and then add other people to that voice chat (or they can join in). Starting a Voice Chat with someone on Windows 10 via the Game Bar is a One-to-one to start, and you can't just start
an "empty" party as you can on Console unless you use the Console Companion app.

This page has a few more details on the Game Bar, but additionally I believe you can still use the Xbox Console Companion App to start a party as well in the more traditional manner.