We checked his teeth and his saddle. It seems like he is doing it on purpose. He doesn't lije contact at all. I am going to pay an instructor to do untensuve ground work with him over December.
Maybe just smack him when he does that? Otherwise just keep him busy
maybe it has sensitive mouth or the bit it has causes discomforst and does not want your daughter to get a hold of the reins so it keeps on snatching them