Final Course still locked

[kirbo_kirbstar]

Hi, I've been playing through this game and really loving it, though I'm confused on how to unlock The Final Course. I completed Level 28 - The Feast and the Furious, and there's a line that goes directly from there to 30 - The Final Course. Do I also need to complete both Levels 27 and 29? I think this is the first time in my playthrough that following the shortest path on the map doesn't align with how the game can progress.

I love this game, but levels take a long time and I don't have a lot of time for this so I'd like to know the quickest way to finish this instead of testing around myself.