Safari fonts not displaying properly Safari 12.0
macOS Mojave version 10.14
MacBook Pro (13-inch, 2017, Four Thunderbolt 3 Ports)

AS of today (2/11/2018) characters in Safari are being shown as boxed question marks.

The same websites are displayed perfectly in Firefox.

Emojis are not displayed in Messages main window but in the sidebar they are!

I have tried restore default fonts etc but no difference.

Any help appreciated.
My experience is to check the font in ‘font book’ one by one on preview display mode ⌘+1.
Just use up arrow and down arrow to quick check fonts.
If you find some font like the picture below ,delete it then reinstall may help.