I go to the owl sign, go the directions, and end back where the sign is and no monster appears. Is it a monster that moves around?
No, it's a monster that's in front of the sign. I'll take a look at this on my end to see if it might be a bug.
Edit: I've double-checked the code ran through the puzzle and made sure to do it incorrectly and then I just reset the puzzle by interacting with the bird again to do the puzzle with the correct directions of up, upper right, right, and left. The monster appears in front of the bird.
I could narrow this down on my side with your save file/data that would be easiest for me to figure if there is a bug at this point.
If you're still having problems could you post the saved data here so I could take a look at it on my end? https://www.file.io/