That Interpolate GN culls the guides based on density which depends on size of mesh. So your example is expected behavior.
For the hat you can check the following:
- does the “surface” object and UVMap in the modifier panel match the surface adn UVMap in the Curve Data panel?
- Is the UVMap unwrap good or broken? - if the unwrap has a issues (e.g. overlap) then the hair will have issues.
Alternatively consider making your own interpolate GN which doesn’t cull the guides… maybe something like this where the density is determined by the resample length:
Or copy the Interpolate GN and customize it to your needs.
Good luck.