Would you mind verifying the credentials are correct by installing a package from that extra index? To ensure it's not being installed from PyPI, you can use uv pip install --default-index or pip ...

But there’s a feature unique to the Python edition of Windows that makes it easier to manage multiple installed versions of the Python interpreter—the py launcher.

Who can help? After a clean pip install transformers==4.51.3 tokenizers into a fresh virtual environment on macOS ARM64 (M2 chip), the class DataCollatorForCTCWithPadding cannot be imported either ...