Image height is fixed

My client has purchased the paid version after I suggested that she should purchase it. I deleted the free version and installed the paid version. When I set the Image behavior to Natural in the general options, it does not seem to work. The height of the slider is fixed and my images are being resized. Images which are larger are squashed vertically. Is there a way to have an auto height for images? I tried entering auto in the slider settings but it doesn’t accept auto, instead it sets the height to 0. We want to be able to add images of different sizes (vertically) to the slider.

https://ww.wp.xz.cn/plugins/slider-image/