https://wccftech.com/windows-10-20h1-build-19002-1002-fixes-restart-shutdown-issue/

Microsoft has today released an update to last night's Windows 10 20H1 Insider Preview Build 19002, bringing one fix for the issue that was causing some devices to get stuck during shutdown or restart. Windows 10 Build 19002.1002 carries the same changelog released with last night's Build 19002.

If you are still experiencing the problem, check out this forum post for a workaround to the Windows 10 20H1 shutdown/restart issue.