I can't seem to add any fonts to an existing web project. Was trying specifically with Source Sans Han and while the web project appears in the dropdown to add the family to the project, the web project is greyed out and not selectable.
Thank you for reaching out, and sorry to hear you're unable to add fonts to the existing web project. I am unable to reproduce the issue at my end.
Have you tried signing out of fonts website and signing back in? Are you unable to add font specifically to this project or any of the projects? Could you please try creating a new project and then try adding fonts?
I tried these things. It actually looks like the issue is specifically with the Source Han Sans CJK fonts - I've tried the Japanese, Korea, and Traditional Chinese ones and they can't be added to any project, even a new project that I created.