Re-check validate_imagestack function
B writes:
@merlijn.wajer: just poking around your new code python deriver code: https://git.archive.org/merlijn/python-derivermodule/-/blob/master/derivermodule/imagestack.py. It looks like it wants filenames to be particular. ID_dddd. I believe this should all work fine if they are just handled in sort order, and not with particular named files inside the zip. @H would know more, but we have tried to make it easy on people to zip up a bunch of images and put it in an item and have it work.