Featured Image Issue

I have a question on something that I CANNOT figure out on the newest website I’m working on for an animal rescue. I’ve put a masonry grid on the site of posts, so that each new post shows up in a block with a picture and an excerpt. I cannot figure out why the featured images will not stay the same size. I’ve set the settings>media for thumbnails for the size I want, I’ve set the customization for media for blogs to be the thumbnail size I want, I’ve read about the featured images and how to set them all the same size for two days and all the settings are, I believe, how everything says it should be…..on the most recent post, I even resized it to the correct dimensions (250px) BEFORE UPLOADING so the image itself is no larger than I want it to be……and that one posted as larger than any of the others! The sizes are all over the place, lol. How do I make them all come out the same size every time, so the blocks all look nice?

As you can see, under the “success stories” section, none of the images are the same. The most recent one, a kitten named Silver, is the one I resized to be only 250 px before I even uploaded it to the media file, and it’s larger than all the others!

What am I missing?

The page I need help with: [log in to see the link]