Certified GKH Gardening Expert
It can be hard to say without seeing the damage. This can be caused by, both, underwatering and overwatering. It can also be caused by a lack of phosphorus and potassium in the soil, or too much nitrogen.
Heat can be a factor, as well as low humidity. Both can cause a lack of fruit.
These articles will help: https://www.gardeningknowhow.com/edible/vegetables/beans/bean-blossoms-no-pods.htm