SplineMesh does not apply NavArea along its entire length

I’m trying to use a NavArea on a static mesh to alter how the AI perceives roads. The roads are going to be placed at runtime as splines. The problem I’m running into is that the NavArea doesn’t confrom along the SplineMesh as can be seen below.

The purple color shows that the NavArea is there but it only shows up in the starting position of the spline’s static mesh. All SplineMesh position setting is occurring in the construction script of the actor.