It just happened to me that after uploading an image (a portrait oriented) in the WordPress (version 4) admin page, the image was rotated. I tried to edit the image, by clicking on the Edit original image, but image simply didn’t load. When I opened the url the placeholder pointed to in a new window, it was showing a “-1” instead of the image itself.

I could solve this problem, by opening the image file in an image editing software and saving it as a PNG file, then reuploading. Then the image was loaded well.

It seems that the problem happens with photos taken by devices which has accelerometer or other similar features (ex. smartphones).