Eric in Customer Service received a call recently about our Royal Corona beans not cooking. This confused us as we know exactly how old these are (we keep the lot numbers handy and we haven't had this bean for long). The caller cooked the beans for hours and they weren't softening. No salts, no acids, no reason! Then she said, "And I soaked them for 24 hours so they really should have cooked fast!" Bingo! There's the culprit. Whenever we hear about cooking problems, they always seem to stem from oversoaking. It's not intuitive but it seems to be the reality with our beans.
If you want to soak, I would suggest from 4 to 6 hours.