All the answers above are helpful but none solved my issue. In my production file, my STATIC_URL was https://<URL>/static
and I used the same STATIC_URL in my dev settings.py file.
This causes a silent failure in django/conf/urls/static.py.
The test elif not settings.DEBUG or '://' in prefix:
picks up the '//' in the URL and does not add the static URL pattern, causing no static files to be found.
It would be thoughtful if Django spit out an error message stating you can't use a http(s)://
with DEBUG = True
I had to change STATIC_URL to be '/static/'