Posts slider is not cropping images properly

On my front page I have a posts slider, which i have set to crop the thumbnails to 900 X 450. It was working fine.

However, after i updated the theme and the visual composer, it no longer crops images.

You can test this by adding “Kelsey” to the “categories” section in the posts slider editing box. One or two posts ago the featured image is square, and you can see that it’s not being cropped like it’s supposed to.

Thanks!