Whenever i upload an image (ball.png) wordpress will auto generate a bunch of smaller images that are different sizes. e.g. ball-300x200.png. These images display fine, but when i set on of these images a featured image it shows up as a broken image. When i set a featured image for a post it uses the base image "uploads/2015/07/ball.png", but this image does not exist. All of the other size variations of this image exist, but not the main image. This happens for every image that i try to upload.
All of the thumbnails generated when i upload an image are valid images that are smaller versions of the main image. Im not sure why the main image is going missing.
Im running wordpress under IIS 8.