Problems with seams in Spline Meshes

I’ve been having some trouble with seams on splines with static meshes. I have a seamless mesh but when it’s splined it creates a nasty seam between the pieces of geometry and, depending on the lighting situation, it can be really noticeable. This is the geometry with a basic color material (to rule out an issue with the normal map), and production quality lighting, which seems to be blotchy for reasons I haven’t figured out yet (the lightmap resolution is 64).

And this is the same geometry in the same scene from behind.

A seamless normal map does nothing to help the situation.

I’ve checked the mesh over in Maya and adjusted the normal map several times so I’m thinking it has to be something in Unreal. I’m by no means an expert on Unreal rendering so I have no idea what is causing this, or why the lighting is of such low quality on “Production” settings.

Looks like signed distance field shadows where the end of mesh is missing the neighbor sample and cannot interpolate an accurate enough shape. Experiment by increasing the lightmap resolution until the problem is gone.