when i export a UFO from glyphs, change the kerning in Metrics Machine (or whatever), save it, and then re-open it in Glyphs (to add another glyph etc.) i cannot save the UFO again. it gives me an error message, saying:
»-[__NSCFDictionary setObject:forKey:]: attempt to insert nil value (key: com.schriftgestaltung.weight)«
can you help?