I honestly think there is something wrong early during meiosis when the spider gene is homozygous. I think for the same reason it causes neuro issues, It doesn't copy properly and therefor doesnt develop properly if at all so many don't develop enough to be laid or if they do, most are slugs. I think the white snake people were seeing were just the result of a homozygous animal that made it further but still not being fully developed. Just my theory.
Side note though: I believe pinstripes were proven to have a viable "super" by more then one big breeder. I won't be the one to drop names as I'm just going off of what I heard