coveralls doesn't recognize relevant lines, says coverage 100%

Github action execution: https://github.com/lpenz/ptvertmenu/actions/runs/6699984703/job/18205107235
We got the following result (printed under lpenz/ghaction-pytest-cov):

   Name                                  Stmts   Miss  Cover
  ---------------------------------------------------------
  src/ptvertmenu/__init__.py                5      0   100%
  src/ptvertmenu/vertmenu.py               79     63    20%
  src/ptvertmenu/vertmenuuicontrol.py     114     78    32%
  tests/test_basic.py                       5      0   100%
  ---------------------------------------------------------
  TOTAL                                   203    141    31%

That's uploaded to coveralls. But the coverage result in the corresponding page at https://coveralls.io/builds/63640062 is 100% coverage, not 31%.

I can't really tell what breaks it, because I have the exact same scheme in another module, and coverage works ok:
https://github.com/lpenz/disk-img-tool/actions/runs/6697777869/job/18198389253
https://coveralls.io/builds/63634714
(it's higher, but not 100%)

Start with the GitHub Actions run and its lpenz/ghaction-pytest-cov output, then compare the uploaded data with Coveralls build 63640062. Use the disk-img-tool run and build 63634714 as the working comparison. Done means Coveralls reports the generated 31% total rather than 100%.