I found my issues exactly the oposite -- remember that 1) You cannot mass-set "visible in reflections/refractions" to my knowledge (gotta set it 1 at a time) and 2) Seems to default OFF with most shaders except phong/phong E if I remember correctly. So -- if raytracing doesn't work as planned, check "visible in reflections/refractions" are set the way you want for EACH object.