I have made a new cc food, bread, which sims can knead and bake, then eat. It is all going well except that when the sim is eating a slice, the slice disappears as it is moved up to the mouth and back, and then reappears on the plate. What am I missing here?

Screenshots to show what I mean, and the bread (and serving board) is attached.

Thanks!

edit: it is something to do with having changed the eat with fork (from the cloned food) to eat with hands. Not sure what I have to change to make the slice of bread conform.