I have attempted several times to sort my album images by filename. It's never worked. I setup a naming convention for a group of albums which was very uniform and simple, but when I access the images management in admin, the images still show up in an arbitrarily random order.
Caveat, maybe I'm misunderstanding the purpose of the sort. If the sort order isn't supposed to be reflected on the image admin pages, then perhaps there's no issue here.
(Version 1.4.4)
BTW, the way Zenpage is organized internally has enabled me to do quite a variety of customizations with minimal breakage of unrelated stuff. Very simple and elegant design concepts much appreciated.