I think this is the persistent problem related to the cad model not being very close to x,y,z = 0,0,0. I've not had time to re-export my models to resolve this, but the solution provided by @Jake Weber is working for me (add depth-of-field to the camera).
https://twinmotionhelp.epicgames.com/s/question/0D54z000096cfYYCAY/path-tracer-lines-on-surfaces?language=en_US