The font does not display foreign characters correctly
When generating a pdf you might see some special foreign characters (eg. Ã, Ä, Å) displayed as a question mark (?,?,?).
While Pdf Customiser and the underlying pdf conversion library supports any UTF-8 character the chosen font for the pdf may not include this character resulting in the question mark. To fix the issue, choose a different font under Stores > Configuration > Pdf-Printouts. We recommend the Dejavu Sans font as it has broad international character support or alternatively you want to take a look at uploading your own font.