When the diplomat/princess does the "wave" bit and you get no popup, that means they were trying for something that wasn't allowed. In RTW, that usually meant they tried a bribe but the price was higher than their treasury. However, it could also be an alliance request when it turns out they are at war with some faction that would disallow the alliance, or a request to marry off a princess to a faction heir in either direction, but that couldn't happen because you have no princesses or your faction heir is already married. None of those will bring a popup.