For years we've tried to grow limas of different types. We do pole beans and get what looks like terrific plants, approximately 7 feet high. They run sideways until hardly any light can get through them. Bugs don't seem to be a problem (Our half-runner beans do about the same except that we get more beans, but they aren't prolific. ). Yet, we get very few beans.
Prolific Lima Bean Growth-Few Beans
Certified GKH Gardening Expert
It sounds like you may have a high nitrogen problem. High nitrogen will produce big plants, but few seeds/pods. Have your soil tested and cut back on nitrogen while increasing phosphorus. The phosphorus will help bring the plants back into balance so they can fruit.