Conversion deletes half of the text

Hello,

I am trying to convert this ebook from epub into mobi.

So far, so difficult. The ebook (please ignore the language for now) once downloaded as epub by hovering over the "ebook - free" button looks OK despite a fair number of scanning errors that I am willing to deal with for now. But when I try to convert it to mobi (or any other format, for that matter), more than half of the book text -starting just below the cover - is amputated.

I have the suspicion that it may or may not have something to do with the original´s gothic script (note that the epub features a "normal", standard font).

I tried randomly tweaking conversion options, alas to no avail.
Could anyone offer a clue to very clueless me?
Thanks!:thumbsup: