Question - Have you tested this family in a new game? I don't know why I didn't think of this before.
When odd things like this happen I export the family and their house, most of the time separately, do a factory reset and then create a new game, install the family and house to see if that has helped. Most often a factory reset helps.
Would you mind sharing the family to see if I can run into the glitch with them? If so, attach them to your post. After I've downloaded them, you or I can delete the attachment if you'd like.
MrsFlynn