Could be along the same lines as my fructan sensitivity. Corn is high in sorbitol which some can have intolerances or sensitivity to. Some people can get away with a small serving and certain processed forms, while others have to avoid it altogether. I think it's one of the few FODMAP antagonists that doesn't have an enzyme yet 🥲 Could also be something totally different! They would also potentially be sensitive to peaches, apricots or other foods with pits or seeds in them if it was a sorbitol sensitivity.