Ran into a nice little bug in Chapter 4.
On the giant puzzle map, I was exploring with the bird, and when I went to snap back to Leo, I went flying up to the top right corner instead, and I couldn't move at all. When I quit to the main menu and hit 'continue', it put me at the boss for Chapter 3.
Kinda irritated me.
Still, the gameplay is nice, and the art is beautiful. Kudos to you.