For example, running on a script with the following import statements:

import numpy as np
import matplotlib
from scipy import ndimage

reports only

• _distutils_hack
• numpy
• packaging
• setuptools

This is because an Exception is raised during modulefinder.run_script (which Sumatra ignores, since it's better to get some dependencies than none; however, Sumatra should include the information that not all dependencies were captured):

...
File /Library/Frameworks/Python.framework/Versions/3.12/lib/python3.12/modulefinder.py:69, in _find_module(name, path)
     65     return None, None, ("", "", _PY_FROZEN)
     67 file_path = spec.origin
---> 69 if spec.loader.is_package(name):
     70     return None, os.path.dirname(file_path), ("", "", _PKG_DIRECTORY)
     72 if isinstance(spec.loader, importlib.machinery.SourceFileLoader):

AttributeError: 'NoneType' object has no attribute 'is_package'

This seems to be related to a known bug related to namespace packages in modulefinder, for which there is a long-standard pull request: python/cpython#29196

Since we don't know when/if this bug will be fixed, it might be worth incorporating a patched copy of modulefinder into Sumatra, although probably not the full solution from the PR since that changes importlib/_bootstrap.py, which I'd rather not mess with.