Package Registry returning 400

I’m trying to write a Python package to the package registry in my project, but I continually see the error:

TWINE_PASSWORD=${CI_JOB_TOKEN} TWINE_USERNAME=gitlab-ci-token python -m twine upload --repository-url${CI_PROJECT_ID}/packages/pypi dist/*
Uploading distributions to
NOTE: Try --verbose to see response content.
HTTPError: 400 Bad Request from
Bad Request

My runners are on Gitlab, and this has worked several times before. Going to the URL directly says “invalid package ID”, yet that is the ID displayed in the package registry page.

Is this a problem with my setup or is something about the Package Registry broken?