I believe this is an issue with the creative cloud desktop app, but it affects every app, even when trying to add fonts from the web browser.
Basically when I click the fonts tab in creative cloud desktop app, the loading icon just keeps spinning indefinitely. When I go to the website to add/sync fonts from there, I'am able to activate fonts but they do not show up in any of the Adobe applications. This is detrimental to my work.
Just spent 5 hours on a remote session with Adobe support, they were not able to resolve the issue. They used their cleaning tool to uninstall Adobe CC desktop app, and then re-install. No-dice. They suggest it's the network I'm on, which is a total cop out answer because this problem persists no matter what network I'm on. This is unacceptable. Browsing this forum you will notice that many people have this exact same issue... the only solution being to format/completely re-install windows which is absolutely absurd. This is Adobe we're talking about. And they can't come up with a solution for a problem that is totally crippling to the software suite. Not being able to install/use custom fonts is a big deal. COME ON ADOBE!!