Custom Collision - unexpected results

Hi, I’m trying to make custom collision for a simple rectangle and am getting results I don’t understand. Here is my source mesh (mesh and collision mesh are exactly the same, collision mesh uses UCX prefix):

Here it is imported to UE:

Wireframe shows the mesh is exactly the same as source, but as you can see the collision mesh is a mess. I need the collision mesh to be exactly as authored as I am using it as a spline mesh (think platformer). Am I missing something?

Bump. Is this an expected result? I’m confused by this.