For anyone still having the issue, I'm tracking the problem here. https ://mrmacintosh.com/big-sur-11-0-1-rc2-full-installer-an-error-occurred-installing-macos/

@wjpjr is correct. Big Sur beta 4 does not include the required updated drivers for the new 2020 iMac. You will have to wait until Public Beta 2 or Developer Beta 5. https ://mrmacintosh.com/big-sur-beta-not-showing-up-in-software-update-troubleshooting/

Yes, Finder is a mess on beta 1 and 2.

This might mean that you are in the CustomerSeed. Big Sur has not been released as a public beta yet. More info here. https:// mrmacintosh.com/big-sur-beta-not-showing-up-in-software-update-troubleshooting/

Some accounts are having login issues on Big Sur. Until the issue is fixed it's recommended to have 2 accounts.

Beta 2 for DTK is not available yet.

For anyone else having issues getting the latest Big Sur Beta going. https:// mrmacintosh.com/big-sur-beta-not-showing-up-in-software-update-troubleshooting/

The setup assistant should automatically unlock your volume by asking for your password. You don't want to do that though, as you wan to erase the entire partition and then reinstall Catalina. To erase the drive you do not need to unlock the drive, just click Macintosh HD and then hit erase. You will be asked to erase all volume groups, be sure to do that. Then you can install catalina.

I have the fix listed under section 4 https:// mrmacintosh.com/big-sur-beta-not-showing-up-in-software-update-troubleshooting/

You need the latest BridgeOS update to boot to Big Sur Recovery. Since you are still on an old version, recovery attempts to update it first. The update fails because the Big Sur BridgeOS version is not available or is not working correctly right now. The only way to perform a fresh install is to upgrade from Catalina (bridgeOS updates to newer version) then you can perform fresh installs.

This is a problem for sure. When this problem happens shutdown your Mac and restart, the password should work in system preferences again. Touch ID will not work but sudo will work in terminal when you are having the problem.

Yes, Big Sur Beta 2 is now available and it is 9.55gb in size. If you have Beta 1 installed you can click upgrade and you will be on Beta 2 when the installer is complete.

I tried to put all the issues with Big Sur Beta that had to do with download issues, install & availability all into one article. https:// mrmacintosh.com/big-sur-beta-not-showing-up-in-software-update-troubleshooting/

I wrote about all the issues that a user could have when trying to update to Beta 2. mrmacintosh.com/big-sur-beta-not-showing-up-in-software-update-troubleshooting/

I just finished updating my article with the latest info. Please let me know if I have left anything out. https://mrmacintosh.com/how-to-install-macos-big-sur-beta-on-vmware-fusion-parallels-desktop/