That's it, I'm on Mac Mojave with weasyprint-44, python 3.6, and Cairo etc. versions match. The PDF renders nicely otherwise - symbols and letters are fine - just no numbers?
So weird.
Can anyone point me in the right direction?
I was able to fix this problem by eliminating the font "Segoe UI Emoji" from a font-family CSS declaration. Numbers started appearing again once this font was removed from CSS.
The bug seems to have started with some change on macOS 10.14.4.