Sophie Kate is the same way, when the harness and leash is on but "in hand" she will stand still but them minute its up and someone is holding it she will walk. I am not sure why but it sure works out well at times.
As for training to walk on a leash, I took puppy classes and they showed a way of motivating the dog to walk on leash by rolling a ball and walking with the puppy to get it. With that said that was only used to get them moving, they do not want the puppy to pull on the leash, Sophie Kate will walk on my right side only and not on the left (I think that is because that is the side I used when training her).
__________________ Cheryl,Mom to  SophieKate |