Box Trace detects mesh only when it hits edges, not triangles

I have a mesh which is a race track made in 3DSMAX by lofting a shape along a spline, I imported it in UE as static mesh and so far so good.
The issue comes when I use a box trace for objects: the trace doesn’t detect the mesh always. The trace sees the mesh only when it hits the edges dividing its triangles but not the triangles themselves.
The mesh is configured to use complex collision as simple and I’ve tried a million of different settings but with no luck so far.