Problem solved by switching from "The Ancient Galaxy" to "(Default)" in "Change Theme" of the Main Menu. Thanks for support! Cheers.

No mods running and the game is installed on brand new PC... Can I assume it's not a common thing around latest updates?

I've just found DW:U(steam) "Way of the Ancients" government type(haven't played DW:U for more than a year) is already unlocked within new game setup and even during a game without an appropriate space discovery as it used to be. Is this a new feature or just a bug?