I haven't had time yet to read all the posts and may be saying the same thing someone else did .... but, even though I soak my beans, or not, ... if I don't cook them a couple hours or until tender .... they will never soften up in the sauce, no matter how much longer you cook them. They need to be tender before you add whatever you are going to add. Mostly this happens with white beans.

If I load dry red beans, along with a piece of ham, celery, onion, etc. and cook in the crock pot, they are nice and tender. I don't even soak them. Nor do I soak pinto beans.

At least the dogs ate them. Try again! It is all good.

Lots of dried bean, and in particular red kidney beans, need to be brought to the boil before simmering in your crockpot. That might be the problem.

I haven't read all of this, so some one may have answered: the sugar and the tomatoes don't let them soften, and will actually make even soft cooked beans tougher. Add the sugar and/or tomatoes at the very end. As for gas, to 2 quarts of cooked beans, add a 15 ounce can of crushed pineapple. doesn't change the flavor, but eliminates the gas. Also, when I'm cooking beans, I cover them with cold water, bring to a boil, you can even let them sit overnight at this point, then drain and rinse the beans very well, cover with cold water again and simmer until soft. discarding the soaking water also reduces the gas.
Old beans take longer to cook, but even 20 year beans I have cooked to softness, soak them overnight first, without seasoning.

You can buy the 15 bean mix in our grocery store and I think Wal-mart. They are so good!!!

I would take them and cook them on the stove to see if they get done.

I have found the lighter the pinto beans in color the fresher they are, the dark ones are old.

I don't think dry beans go bad
I've used dried large limas that had been in my pantry for probably 4 or 5 years.
Soaked overnight in 8 cups of cold water - no salt
Add thinly sliced onions to pot the next day and bring to boil, cook uncovered on low flame for an hour before putting in a casserole with all the addditional ingredients to cook in oven for 2-2 1/2 hours.