Pike57,
Windows Update allows uninstalling individual updates. Under Windows 10 in the Update History, I see two updates on Aug. 9 and two on Aug. 10 before the install of version 21H2 I initiated in hopes it would fix the problems. There were also a huge number of security fixes to various Office products. Did you try uninstalling the Aug. 9-10 updates before scrubbing and rebuilding your system?
I would paste a screen shot of the file names here except that PrtScn seems to be gone and without the Start Menu, I cannot easily reach the snipping tool.
The Aug. 9 updates are the Servicing Stack 19041.1852 and the Security Update KB5016616.
The Aug. 10 updates are Update for MS Windows KB5105730 and a Security Update KB5102170.
If you or others think rolling back these updtates could help, would you first uninstall the version 21H2 install as well?
Thanks for your responsiveness.