-
Download the ZIP https://github.com/googlefonts/roboto-flex/archive/refs/heads/main.zip
-
Unzip and from
sources
folder openRobotoFlex.designspace
When Glyphs 3.0.5 (3120) opens it, I get this:
(There is also a problem with rendering the master switching widget — it’s pushed to the very right of the window in a somewhat odd way.)