Thank you Alyssa!
I had problem with the current stable version, reinstalled current stable version, then I tried to install the RC just to test if it worked.
Your feedback suggested that there is no problem with the 1803 itself, just the way it was installed (got entangled with some previous updates or some more arrogant apps mcafee, icloud etc)
I restarted and installed the Win10 update again, and Axure (stable) stopped working again.
The system restore & update messed up a few more things, I was not even able to uninstall or install Axure after that, any normal way (via Axure installer, control panel..).
So, clean slate, Windows reset (I had just a few applications on this machine, so not a big deal), reinstalled all apps, including Axure, it seems to open fine.