Probably a bug. I also had the same problem. I pressed space bar all the time until I recognized through the background music, that I'm not in the scene anymore. Then I opened up the menu, scrolled 6 times down, pressed spacebar, then scrolled a bit down and pressed spacebar again (if you are wondering, I was just saving the game, by using the sounds, to coordinate myself to the right buttons).
The I pressed f5, restarted the game, and selected the save file I was recently creating and boom: you can see the screen again.
But unfortunately, if you try to play the scenes in the memory room again, then the black screen bug will appear again. So yeah, we need a bug fix to solve this problem...