I created a new file in Glyphs, turned off exporting for all characters, (apart from
.notdef) and exported as OTF. See: ttx-669.zip (1.8 KB)
The font gave
ttx a headache, and Khaled says:
I think the CFF table is broken. It uses a predefined charset (id=0, ISOAdobe) and the spec says:
A font may use a predefined charset if it exactly matches in the first nGlyphs
But the font has exactly one glyph, so it does not match the predefined charset.
So over to you.