I have the same problem. Only “Standard Web Fonts” show in the Font Family drop down. The wonderful long list of google fonts has just gone! Comparing it with my localhost installation of same theme(longform) where it works, I have not only deactivated but deleted ALL font plugins (WP Google fonts, Google font manager… etc).
Will attempt to deactivate one by one all plugins and see, and come back with results.
Note: Interestingly, text in site added when the drop down was showing Google fonts, is still rendered in my choice font. The newly added text, but goes to some default theme font. I wonder how does that happen.