Dir1 and Dir2 curves influence: Global
Tangent Type: Curvature to Face
Dir1 and Dir2 curves influence: Tangent Influence
Tangent Type: Curvature to Face
The flow of the boundary surface is curvature continuous but you might want to inflate the surface more to change the pattern of the zebra stripes. Think of the surface as a balloon that you need to inflate more.
This issue exists for very rounded shapes.
When you set the influence to Tangent Influence, you can see the zebra stripe pattern change.
Tangent Influence helps inflate the surface for very rounded shapes.