Suddenly in Minecraft Beta

Do you have multiple users on your computer?

No. Me and my son share the PC, but he logs onto my Windows account and then loads his Xbox profile. He's only 9, so there is no way he'd know how to load Minecraft Beta

That is quite interesting, since it's not installing on any of my computers (when reinstalling, I get 1.17.41). It is possible that reinstalling might roll you back, but make sure to back up the %userprofile%\AppData\Local\Packages\Microsoft.MinecraftUWP_8wekyb3d8bbwe\LocalState\games\com.mojang folder first, as that folder contains all your worlds (and other things)

Just uninstalled Minecraft and then reinstalled from Microsoft Store and I'm still in Beta. This is very odd.

Have you tried the Microsoft Store Troubleshooter as well as reinstalling the game under your Xbox account as well as your son's?

You have to enroll each individual device in the beta. Enrolling an Android phone in the beta does not enroll a Windows PC in the beta.

Try running this command in Admin PowerShell:

Get-AppxPackage -allusers *minecraftUWP* | remove-appxpackage -allusers

After running this command, reinstall Minecraft and see which version you have

Just tried it - I found the link to it on the Xbox Insider Hub just before your message. It ran OK, but the Beta version was reinstalled. I only reinstalled Windows 10 a couple of weeks ago and I'm loathed to go through it all again in the hope it sorts out the problem for a game I play for a few hours a week.
I've not even signed up for Beta this time around, which is the thing that gets me. In fact, as I mentioned, I'd not even downloaded Xbox Insider until an hour our so ago in the hope of fixing this!!

Thank you for your report!

However, this issue has been temporarily closed as Awaiting Response.

Is this still an issue in the latest version? If yes, can you please add it to the affected versions (or mention it if you are not the reporter)?

This ticket will automatically reopen when you reply.

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Cleaning up old tickets: This ticket had been set to 'Awaiting Response', but has not received a response from the reporter (~3 months+) so is being closed as Incomplete. If you feel this is still a valid issue then please comment, or create a new ticket following the Issue Guidelines which includes steps to reproduce the problem.

For any account or purchasing related issues, please contact Minecraft Customer Support directly, as we cannot assist with those here at the bug tracker.

Quick Links:
📓 Issue Guidelines – 💬 Mojang Support – 📧 Suggestions – 📖 Minecraft Wiki