Thumbnail sizing inconsistent

I use Cyclone Slider on a clients site and use the thumbnail template. The last few images that I’ve uploaded, the thumbnails are 100% crops instead of resizing the image to fit inside the thumbnail (as he’d like them to be). You can see the unwanted zoom effect on the last 4 images here: https://geraldwells.com/images/

Please advise on how to solve this issue. Thanks.