Steps:
1) Upload a file and accompanying screenshots, and submit it.
2) After the file has been submitted, select to edit the submission.
3) On the submission edit page, notice whether any screenshots have been rearranged.
4) If the submission edit is applied, any screenshot rearrangement is implemented.
I specifically used ~10 linked gallery images for the screenshots, although I would think that any linked non-gallery images could also encounter the same issue.
Out of several dozen submissions, the issue occurred on the vast majority of them, although I think there were one or a few cases where it seemed to not occur.