Would that trait be from the bitch side or Sire side?
Most likely both; It's generally believed to be genetic recessive, not sure there much research into pinpoint the gene. Affected individuals can only ever be males, females don't have the necessary equipment to see the condition. As most males with the condition will not be bred, they are cut out of the population. Males that might still carry the tendency but not show it, will still be bred, females carrying or affected (as it cannot be seen) will continue to be bred. Thus the condition, could go forward in both but statistically would be more likely to remain hidden in females. Unless a gene were identified, the only option is for breeders keep track of their stock, and look at both sides. Still by the time you know if you've produced such males, you already have a litter with individuals that could be genetically prone to the trait. Was it the female? the male?, or the combo? Basically a big ole mess, that if genetic will most likely continue on. Research-wise, funding is more likely to look at genetics related to detrimental or incurable conditions, however this one is easily corrected and only affects individuals that wish to breed later. Unless research is put into it to prove it's genetic and that there's a gene that can be screened for; Not much that anyone can do except keep records, research lines, and not redo breedings that result in the condition.
Interesting read
http://www.instituteofcaninebiology.org/blog/cryptorchidism-is-complicated