In the "Creepy Crypt" level, near to the end of the level, there is a gated exit to the dungeon. Although the gate is meant to block off the player from travelling out of the crypt, the player is still able to interect with it. Once interacted, the player is able to go through the same area as the previous forest level, however is unable to advance by interecting with the previous level's exit door. When the player returns to the enterance of the area, via the crypt door that leads to the gated area, they are stuck inbetween the travel point and the gate, stopping them from being able to complete the level. 
Edit: I found out it was because I was able to pass through the locked gate without first obtaining the lost tome, which stopped me from meeting the requirements to leave the level.