fonts uninstalled and won't reinstall, despite restart

Fonts have uninstalled (no idea why) and when I try to re-install i get an error saying there is a conflict. I have already installed the latest XD update, signed out of CC, restarted, and signed back in. No change. (I have never had trouble with fonts before. I had installed the font using Font Book previously...not sure why I now suddenly have to manage it in CC and it won't let me.)