Oo, karamihan ng babies actually struggle with that transition kasi ang lactose-free milk mas matamis at may different taste talaga compared sa regular milk! One of my mum friends tried gradually mixing them, like 3/4 lactose-free, 1/4 regular para slow-slow lang, and her baby eventually adjusted after a couple of weeks. Have you tried doing it gradual or maybe warming it up a bit, sometimes temperature makes a difference din sa kung papayagan nila or hindi?