I’ll raise it as an issue with the course staff. But do not expect it to be fixed quickly, because it’s probably something Coursera will have to fix (because it’s their platform, DLAI only provides the content).
We mentors actually do not provide technical support, but here are what I can think of for your consideration:
Use your browser’s Print feature to print it like any web page into a PDF. Please make sure whether the resulting PDF is what you are looking for, or
Do as Tom suggested to download all files, so that at least you will keep the notebooks after your subscription ends and you can figure out how to convert them into PDFs later.