Hi,
I've played Hollow Knight before on my desktop and all was fine, but this time around playing on my laptop, once I reached the Hollow Knight boss the sprite is literally just not there. The battle starts, you can hear all of the sounds, you can vaguely tell where the boss is from the vague particle effects around it, but the sprite itself is just not there at all.
I've tried restarting the game, the computer, and verifying the game files, but nothing seems to have come out of it. Any idea what else I could try to fix that?

Never heard of this, but try re-installing the game without removing saves, if you haven't already. If that doesn't work, it might be an issue with the save file.