using \geometry{headheight=1cm} results in wrong layout for grading answers (Bug #765)

Setting the headheight=1cm in \geometry causes the layout of the boxes for automated grading to be shifted after the first page of the subject. As a result, automated grading does not work (except for the first page of the subject). This seems to be the same issue as described here: https://project.auto-multiple-choice.net/boards/2/topics/6946

Version:
- AMC 1.4.0-1
- Debian 4.19.171-2

Steps to reproduce:
- Create a new project, using the attach minimal .tex as a subject.
- Update the documents (create pdf subject and calage layout file)
- Check the layout of the second page in the GUI, or attempt to grade an image of the second page (scanned or other).

Expected behavior:
- The layout should line up with the boxes of the subject.

Observed behavior:
- The boxes are shifted to the bottom. The shift increases with distance from the top (as if the layout was stretched). See attached partial screenshot of the file cr/page-2.1.jpg.

Note:
- Removing the line \geometry{headheight=1cm} from the subject, or using options (as long as they do not include headheight) in \geometry removes the problem.
- If anyone has an idea on how to correct the bug and still grade the 60 or so papers I already received from my students that would be amazing!