The blue square is an obstacle. It's trying to find a path around the obstacle.
Yes has intended, but the obstacle map is small, the same size as the blue square (64px).
Does the result differ when you change the cell size?
Nope. The cell size is currently 16 px but no matter the size the result stay the same.
There is plenty of room for the pathfinder to find a path in a straight line to the green square. But when the blue square's image point enter the yellow one, the path goes from zero node to one node for... reasons.