Windows 11 Insider Build 29683.1000 - Explorer.exe does not start automatically after sign-in

Windows version: Windows 11 Pro Insider Preview Build 29683.1000
Issue: Black screen after sign-in; desktop and taskbar do not load.
Temporary workaround: Running explorer.exe manually from Task Manager restores the desktop.
Troubleshooting already performed:
DISM
SFC
Registry verification
New user profile test
System Restore
Attempted in-place repair installation
When the issue started: Approximately 1-2 months ago.
The ISO download and repair installation could not be completed.
Help is required.

Pradeep Kumar Bebarta