[Jam]

I get the same problem when using the ebook-convert utility

Here is my one liner script

ebook-convert \
book_name.epub \
book_name.pdf \
--embed-all-fonts \
--paper-size=a4 \
--pdf-add-toc \
--pdf-page-numbers \
--pdf-sans-family \
--pretty-print

It used to work. I converted lots of epub books to pdf with this line in the past, but not any more.

Has the same issue as described in OP above.

Random, but specific letters are transparent, making the pdf export unusable.

For about 5 months (?) this problem has existed.

It's not the epub files, because pdf2go can convert them all successfully.

But pdf2go deos not produce a TOC, and does not number the pdf pages, so it is pretty useless.