Thumbnails are incorrectly cropped

I have a properly cropped 150×150 thumbnail for all my posts and I have set the plugin to use 150×150 thumbnails (to match my existing size).

However, for the related posts thumbnail, it looks like the plugin is re-cropping the image instead of using my thumbnails. As such, they look pretty bad because they are cropped in odd places. Is that just a function of the plugin? Is there a way that I can designate my thumbnails as the primary instead of the awkwardly cropped ones?

https://www.ads-software.com/extend/plugins/nrelate-related-content/