I’ve had a similar thing happen with this style meal before, which I should have remembered because this one factor spoils the whole meal. Everything cooks as instructed apart from the potatoes regardless of cutting them into small 1cm cubes. So you’re left with a fish pie full of raw potatoes. Everybody goes hungry because they don’t want to eat or pick out lots of gross raw potatoes! I’m assuming it would be a lot better if the potatoes were boiled or mashed first ?