I uploaded an image my-image.jpg of dimension 1280x854, after that, I went to Dashboard > Media to crop it to 854x854. (Apply changes to All Image Sizes.)
This however only change its thumbnail in Media Library, when I click the thumbnail, the popup window shows still the original image, before cropped.
In the Uploads folder, I have verified that the cropped image files are existing, with name like my-image-e15249112352.jpg, my-image-e15249112352-854x617.jpg, etc.
I tried to get the image by its id:
wp_get_attachment_image_src(3629, 'large');
The expected return is the cropped image, but the actual return is the original image, like I never cropped the image.