"Sign into an account with access to this sandbox"? Console isn't in the preview program.

For whatever reason the Xbox Preview Program isn't working for me. My console is enrolled in the program and I can't access the new UI/features. On top of that I can't even contact the Preview Program Engineers through the forums because every time I try
to access the page it says "Group Not Found".

Hey Flik Triplez!

You'll wanna post on the Preview Program Support forms as Mister Beep suggested. They may have answers to questions you have pertaining to the preview program.

Be sure you're signed into the account that was originally enrolled in the preview program before trying to access that forum.

I also need access to the forum. My console/account is registered to the preview program.

Hey, l Kevin OG l! It looks like your account has only been invited to the preview program. I've got you the proper role to access the
Preview Program Support forums. Since you seem to have the most recent preview update, it's likely that there is another account on your console that is fully enrolled in the
program and has your console in the preview. Thanks for posting!

If an Account opted into the preview program for the console but you don't have access to said account any longer, try uninstalling the app from the console through My Games and Apps. If it does not appear there for you, your best bet would be to reset
the console back to factory defaults and start from scratch. That way, the preview program won't install when you reload the console with your account info rather than the account that enrolled in the preview program. Here is a quick How-To for resetting
your console.

http://support.xbox.com/en-US/xbox-one/console/reset-console-to-factory-defaults

Good Luck!

I've tried that. I have fully factory reset the console and logged in with an account that has not signed up for preview. The Dev Mode app still tells me it's still activated.