Reg Entry "PortableOperatingSystem" to the resolution!
Just spent waaaaay toooo long dealing with a failing spinner. After getting a booting clone on an SSd with known corruption carried over from the spinner, I decided to just install Win10 on top of Win10. I was presented with this notice "you can't install windows 10 on a USB flash drive using setup".
Simple solution was to change a registry entry from "1" to "0".
PortableOperatingSystem to “0” from 1