Hello! Unfortunately, it's a known issue for players that have a multi-monitor setup. We're still investigating what's exactly causing it.
Please, try switching back to full-screen by using ALT+ENTER and see if it brings the game back.
Is yours a multi-monitor pc powered by an AMD graphic card, by any chance?
Thank you

Yes, I have multi-monitor and a AMD graphic card and I'm going try ALT+Enter and see if it works, thanks for the fast reply and fix.

Edit: It went full screen but still everything is black.

Temporary workaround (before the fix): start the game -> ALT+ENTER -> quit the game -> start the game again

a decent workaround, at least if you want to put it on a secondary monitor, is to grab another steam program (Borderless Gaming), and it works with *most* games (it does on th is one)....almost the only games i've seen that it very much does not work with are the early lego ones.

No issues here with nvidia card, perhaps it has something to do with amd drivers ?

I have a nvidia 4070 (laptop) with 3 screens - it worked some days perfect.
now the mainscreen is black - alt+enter restart works - so no AMD problem?

i also played the game (with steam cloud sync) on an laptop with onboard intel graphics and 3 screens - and I think i have the problem since I played it there one time, but I can't guarantee that this is 100%