Catalina Times New Roman font shows red exclamation mark in left corner for glyphs. Why?

When I open the Times New Roman.ttf font on Catalina I get a red exclamation mark in the bottom left corner for glyphs. I don’t see this when I open the Times Regular font from Times.ttc. I get the idea that there is something corrupted in the Times New Roman.ttf file, but is there anyway for Glyphs to tell me what?


The TTF is most probably fine. The red exclamation mark means that the OT features in the reverse-engineered .glyphs file are not up to date. I recommend reading this if you want to import existing fonts: