Navmesh generating under ground ?!

Could it be that the ground mesh is bigger/smaller than the collision of the ground?

Hello,

I’m working on an open world with World Composition. I’m using a dynamic Navmesh and invokers to generate it.

As you can see on the screenshot, on this big hill, the Navmesh is generated under the ground.
Not at the rest of the ground level (outside of the hill) but almost at half-distance.

If I add an NPC directly on the landscape (not on a “slab” mesh), the result is the same. As if there was some kind of “max height” to the Navmesh…

Any Idea why ?

Thank you so much !

No the meshes have basic box collisions.
I just found a weird solution here : https://answers.unrealengine.com/questions/965471/view.html
Increase the Cell Height.
I set it at 250 lol. I guess the “cubes” building the Navmesh were not big enough to reach ?