So, this is weird: I launch Stellaris, and it's minimized. Open it up and the loading screen will sow with the loading bar at, say, 18%. It's frozen. But if I minimize it again, and then maximize it, now it's up to 89%.

This continues through the setup screens. If I make a selection, nothing happens... until I minimize and maximize, and then the output updates. Couldn't find anyone else with this problem, and put a support request in, but just in case, thought I;d see if anyone else has had this issue.

Did you try reinstalling? or try on another computer, yours might need some maintenance (like reinstalling windows :) )

You have to repeatedly alt-tab into the settings menu and change it to borderless window mode. It's absolutely ridiculous because there are posts about it since October 2019 in forums...