Something occurred to me last night about this @Bluejay77 - have you ever tried using azomite? I have a theory that beans are uniquely sensitive to mineral presence in soils, and the bean agronomist literature forwarded to me a few years ago by the agronomists seems to suggest that too. Not well formed seed is often thought to be caused by excessive heat or inadequate water - and it may be in some cases - but personally I'm more inclined to believe it's minerals. Beans are known, from a health point of view, as containing a rather high level of micronutrients in their dried state. But they can only contain those if they're present in the soil - I know there are studies published online re: mineral percentages in different bean varieties - and they can vary a lot. Perhaps certain bean types are more mineral 'needy' than others. A sprinkling of azomite might help? And it's not terribly expensive stuff.
Interestingly, when I see seeds that are not formed as well as I know that they could be, it's always tied to a certain location in my gardens - in the late afternoon shade of a big pine tree. So for me, any wrinkled seed is caused by inadequate exposure to sun. The soil in that area is actually more moist than anywhere else.