I once had a friend say the weather controls when the beans will or won't get soft. She believed if it was a non-cooking bean day they could cook forever and would never get soft.
I have always believed my beans stopped cooking when I added the seasoning. I try to be sure I don't put anything but water in them until they are soft.
I have adapted a new low energy way to cook them for anyone who wants to give it a try. I have done it lots of times and it has worked everytime so far. I add water about 2" over the top of the beans, bring the water to a boil, turn off the burner and cover the pan. When I pass through the kitchen the next time I turn the burner on long enough to bring the water to a boil, turn the burner back off. I keep doing this until the beans are soft. I do this as I am doing laundry and such. It is amazing how soon the beans are as soft as if they boiled for hours.