I recently remembered the game exists (I don’t know how it slipped from my mind), so I tried the latest build, and I was suprised at how much it has improved since the last time I tried the game.
The problem was when I decided to switch the game to windowed mode, as I do with most games, and clicked the maximize button. As soon as I did, the “GUI layer” stopped drawing. Restoring the window was enough to bring the GUI back. After a bit more testing, I noticed that the issue also happens when resizing the window. As soon as the content area goes beyond 1920x1080 (resizing one of the directions only does not cause the issue due to the letterboxing). Resizing it back to 1920x1080 or less brings it back, and Fullscreen mode seems to use the correct resolution (2560x1440) so the issue is exclusive to windowed mode.
Thanks for the awesome game.