My sister was playing the game and she encountered a bug with her inventory. This is what she wrote:

"after retrieving the lighter, i returned to the castle and entered. i opened my inventory to check that i still had the lighter, scrolled through to the lighter, pressed z a couple times, then closed the inventory. i walked to the bottom left candle of the triangle pointing up and instead of lighting it, i clicked z to read the prompt about how it's unlit. when i reopened my inventory, all my items were gone. when i exited the castle to see if it would reset anything, i saw the shovel in its original place outside and additionally, all my clues were gone as well.

so far, i had completed each direction down in the well, the lake guardian and the rope inside, the plunger with the toilet, opening the cave and completing the cart maze, the graveyard (+ following the ghost), the clock tree"