Regarding my post “setup.exe aborts after 1 second, with no error message.” :
Nikkin, you’re right : I should have supplied more info.
I finally solved this, by re-installing Windows 10 from scratch (clean, new install).
After this Cubase 10 installed OK.
I will never know what the exact cause of the problem was, because the Cubase Setup.exe gave no error message, which is a shame.