Hi,
I love Calibre and I have been using it for the Kindle. Now I have switched to Kobo Glo, but I sometime buy ebooks from Amazon if they are really cheaper or only available there. In this case, I convert them from azw to epub using Calibre

I have just bought a ebook from Amazon and have been able to convert it to epub. The conversion is very good, except on one point: some symbols (greek letters) do not show if I read the epub on the Kobo (in Kobo I have a square with an interrogation point inside). I have transferred it to iBook and they are visible there.
Is there something that I could do to make them visible ? A specific setting of the conversion module? I have already asked for the inclusion of the fonts and the subset of fonts, in the settings during the conversion, but that does not seem to solve the problem. Is this a desperate situation?
Thank you very much in advance for your help.
Murat