It is probably the fade out effect, but if it's not fading in afterwards, or showing some image/animation, then that scene is broken.
When does it happen & is this a new savegame, or one from previous versions?
Oh yea, I fixed that recently . It will be included in future updates, but try this for now:
https://parodos.itch.io/goblinlayer/devlog/687444/small-bugfix