Not sure if it's user error but I have an issue with Thumbnails on my site. In the example I'll provide via the URL below, the thumbnails all seem to display correctly up until the seventh row, last thumbnail to the right. From there to the end of the thumbnails, they seem to be zoomed in and show a small portion of the full sized image.
Laza, this looks like yet another example of the skin deciding that the thumbnail isn't big enough, so it's using the slide image. But in this case, it's cropping the daylights out of the image, because the CSS includes object-fit:none;
The skin tries to display very small images in 1:1 size if the image is smaller than the available space. I made this exception in order to display icons (e.g. PDF) to display without cropping. I don't know why these images are categorized as "tiny" in your album. They should not. I'll try to find the culprit.
Thank you Laza and Jeff. Also odd, and not sure if it's related but all of the thumbnails in this section are all showing as quite large and almost like they are set to 'Single' in the Image Data section (Default, Thumbnail, SIngle, Full Width). Most in this gallery are set to 'Default".
I made this exception in order to display icons (e.g. PDF) to display without cropping.
I wrestled with that one for a long time, and finally cracked the problem by using things like a PDF icon as a background image on a transparent empty.png primary image, with the dimensions of the empty image forced to match the thumbnail bounds. Pick a background color to match the style.
You can set general rules on the thresholds of the different thumbnail/image types. If you'd prefer not to have full-width images at all use Settings / Story / Images / Single image / Wide threshold = No full-width images. You can also disallow the "wide" images on the "Thumbnail" tab with the No wide images setting.
On top of this, you can manually select how each image is treated in the Edit mode -> Image data -> Treat image as box.