Texture seam created by normal map

I have this nasty texture seam which is being created by a normal map. If I remove the normal texture from the material it goes away. The face normals are all pointing outwards. I’ve tried inverting the Y on the normal map which does nothing. I have exported with face smoothing and on import I’m selecting to use the normals and tangents. I tried texture painting the normal with a smudge brush to no avail. I tried recalculating normals in Blender (facing outwards) - nothing. The normals are kind of facing away on either side of the seam in some places, but the normal texture should be handling that. Any thoughts on how to fix?