Is it possible for a person to suddenly be unable to digest beans, after eating them without issue for a lifetime?

Yes: of course our digestive system change all time so food that could be well tolerated before is no longer welcomed so beans could cause bloating or it depend how it is cooked might not get digested and might come out the same way it gut in you could be experiencing some thing we called spastic colon or irritable bowel syndrome simply watch what you eat food that you might like is no longer like you