So. Last weekend I reinstalled windows again. But this time instead of installing the latest version (Version 2004, 2020 May update), I installed the previous one (1909, 2019 November update). And the problem is gone!
I haven’t updated the system to 2004 yet to see if it brigns back the problem, or it’s only there when you fresh install it. I’ll post here when I do. But it’s clear that it is an issue between that windows version and cubase.