Amended images of same file name are not flushed when called by a view.

I have a content type called 'advert' which comprise a single image field. Multiple adverts are displayed in a views block, and are formatted with the adaptive image style.

If I upload an amended image or a new image with the same file name, I find that the image style is not flushed and the old image is still displayed.

Clearing the cache does not appear to solve the issue, although a workaround is to give the amended image a different file name.

Am I correct in my understanding that D7 has automated the flushing process and that this is a bug?