I appreciate the details, Snake, but it just isn’t working for me. I uninstalled everything that looks like a VS artifact program, ran both VisualStudioInstaller 4 (the latest) and 2, and deleted all folders I could think of that VS might access. I rebooted multiple times. The last attempt I downloaded the ISO, disconnected from the internet (just in case), opened an administrative command window, ran the installer with the command line params and selected to install only Update 2 and C++. Once again, on probably my eighth attempt, I still would up with Update 3 installed…
There’s some kind of Update 3 artifact left on this system that keeps getting used, but it isn’t anything obvious. Something in Windows\Temp maybe?