Photos appearing as blank
Can anyone explain why some of my photos are appearing like this in Finder? The preview image is still there, but the icon is blank (see screenshots). I can't double click to open, but if I right click it defaults to open with preview, and the images open as full images. I tried exporting the images from Preview back to a different folder as JPGs and although they then appeared ok in Finder (including the icon), they also wouldn't open without right click, and when I tried to upload to Flickr, Flickr couldn't recognize them.
Any hints?
MacBook, macOS 10.13