There is no such thing as “Clickable image” on Twitter. You can attach image to tweet, bit just as image It will have no link.
Most probably you are both talking about feature called “Twitter cards”. This feature adds clickable image with some link description to your tweet. This feature is provided by the Twitter itself and has nothing to do with our plugin at all. Twitter adds “Twitter cards” to the posts made manually and to the posts made by the plugin just the same.