Win 10/11 launcher not identifying account/not connecting correctly.

I have replicated this bug across several machines and internet connections, so I suspect it may be account related.

When opening the Windows 10/11 launcher, I am not able to launch either the Java edition or the Bedrock edition.

Aspects of the user experience look like a connectivity issue, namely:

• "Oh no! Something went wrong and we couldn't connect to Minecraft services" flashes on and off constantly at the base of the window.
• My gamer tag avatar icon is missing, looking like a web page that couldn't load an image.

As well as this, when it is 'connected' (i.e., no error displayed), it only gives me the 'Play Demo' option. It is as if it can't tell that I own the games.

I own both the Bedrock edition and the Java edition, and these can both be played fully using the Windows 7/8 launcher.