Thanks for alerting us to this behavior. I reviewed your support case and was able to confirm that a supersized version of the image you provided as an example was not generated due to an apparent glitch during the upload process, so I suspect the same is true for the other images you referred to.
Although uploading errors of this nature should be quite uncommon in the grand scheme of things, our technical team is currently investigating this issue and we will do our best to implement a solution to this issue as soon as possible.
As you have already discovered, if you find that a supersized version of one or more of your images cannot be displayed when you preview a listing, you should generally be able to correct the problem by removing the corrupted version of the image and uploading it again.
We apologize for any inconveniences this issue may be causing.