I am sorry to hear about the difficulty you have encountered on your listings that contain only a single image. I've reviewed the listing you mention and find that you are correct, there is an issue with the supersize image not fully showing the image - that the image is larger than the display area for it. I did some investigation with some other postings and this does not seem to be an issue solely related to the single image in the listing, but when the image layout "Paired Top" is selected and there is only one image in the listing this occurs. I was able to post using the same template without that image layout and a single image without this issue occurring.
As such, I have created a work ticket for our engineers for this issue and will update this thread when we have more information regarding this issue available. I have am also responding to your support case regarding this issue, in a bit more detail.