I'm wondering whether that's indeed the case. It seems that at least some genotype has been identified to cause such a phenotype (https://science.sciencemag.org/content/346/6213/1084). If you know what to look for it would just be a couple of bucks to Sanger sequence it. (Then you don't even have to sequence it by e.g. Illumina, which would still be just a couple of hundred bucks per batch). I don't know what margins they get for these kind of products, but I guess a recall will be quite expensive as well.