I have a sample-of-one answer for this question, at least the one about why they were not selling.
I sold mine because it felt unbalanced and top heavy in my hand compared to the wonderful 9mm model. This is because of the thicker and heavier slide on the .40 gun. And it seemed to have excessive muzzle climb during recoil, compared to other .40 caliber designs.
I realize that the above comments are subjective. But perhaps enough people felt the same way and thus sales were too low for it to stay in production.
“There’s a rattle in my glove box,
A Federal twelve-gauge slug.” – Adam Carroll in song Porter Wagoner