Lead (and only) programmer here. While our loading of jumpscares does have technical problems that we plan on hopefully patching out in the next public release (the jumpscare scene sometimes fails to load at all), I'll admit that this bug of yours particularly puzzles me.
The jumpscare here clearly loads, but, judging from your description, it only plays a snippet of it, while also being horribly cropped. I admittedly have no idea as to how or why the game on your machine is acting like this, and I have never heard this happening from anyone else. Can you please tell me what you're running this game on?