Navigation mesh distance from the ground

[Alhazred]

Godot Version

Godot 4.4.1

Question

I am trying a simple scene to understand navigation.
I’ve got a plane as ground, a box-shaped StaticBody3D with its CollisionShape3D 3m high, baking the NavigationRegion3D’s NavigationMesh I see the hole carved around the “building”, then I added another obstacle with its CollisionShape3D wich is 0.9m high. Baking again the mesh, this second building is not considered as an obstacle, but if I raise this building by 0.1 it is considered an obstacle for the navigation and a hole around it appears.
The minimum height that an obstacle must have is 1m at the moment, but it is too much because I will have obstacles shorter than that, like the 0.9 above. Which option manages this height? Where do I say to the navigation mesh to stay closer to the ground?

[Alhazred]

This is a screenshot of the scene.
The character was set to 1.8m tall in Blender, the yellow-ish structure, made inside Godot, is 0.9m.
The navigation mesh is at the character’s waist, at Y = 1m, although the Cell Height property of the navigation mesh is set to 0.25m.
The position of the NavigationRegion3D is (0, 0, 0), the position of the navigation mesh is (0, 0, 0), the ground (child of the naigation region) is at (0, 0, 0), all the scale factors are set to 1.0, shouldn’t the navigation mesh be roughly at 0.25 from the ground? What am I missing?