Hi
I've found a commercial book which uses a subset of four Liberation Serif fonts. Calibre do not display them correctly, while it's OK for ADE 1.73, Azardi, Prince.
I downloaded from FontSquirrel a new set of Liberation Serif fonts, installed them on the EPUB and using the Editor made a subset out of them. Everything is now displayed OK but the question remains as to why Calibre choked on the original subset.
In the original EPUB, I also found some minor mistakes (you said commercial?
) like using as a font-family name LiberationSerif instead of the inside coded "Liberation Serif ", a wrong Mime-type in the content.opf file.
Question: Is there a way to analyze technically a subset as to learn what happened there? I extracted the original subsets from the EPUB and uploaded them here on MR. As you can see, two of the four fonts are nearly empty (in fact the book does not use Bold and BoldItalic fonts at all). Is this the reason?