My lima beans are growing and producing a tiny bean, but will not grow any further. The plants are in the sun all day, so maybe that is the problem. I have had soil tested and haven't found anything specifically wrong. I have also tried different types of soil, but still have the same problem.
I have had the exact same problem in N. Delaware - tried three years; finally gave up. I have heard from veg specialists that the soil/weather conditions need to be 'exactly perfect' for the beans to grow into full size limas (like you - I got micro beans - but nothing more; lots of beautiful, lush foliage, though!) - this was told to me by the professional Horticulturalist for the State of DE who works with commercial vegetable farmers; he himself has also been unsuccessful in his home garden, which is why I myself gave up (if HE can't get them to grow, there was no hope for me). Another specialist told me 'stinkbugs' sometimes attack lima bean buds, which cause the beans to die. Sorry to not give you a better answer!