Hi Glark,
Could you please run the regenerate thumbnail plugin once and try it again. https://wordpress.org/plugins/regenerate-thumbnails/
If you still have the issue, provide me your wp admin details via our private content box below.
Thanks
Thank you @serkan. I did that but I don’t think it’s a case of the image is being displayed incorrectly in but rather “fit row” uses a 16:9 (or so) aspect ratio but “masonry” uses a square 1:1.