Hi,
The attached BadCharacters.pdf displays properly in other pdf viewers such as Adobe and Foxit but has some bad characters in Spire's WPF PDFViewer (Version 2.10.17.4240). The BadCharacters.png shows the difference in the displayed formats. Please let me know if there is a workaround for correcting the problem while you work on fixing it because I have users who are relying on this previewer.
Thanks,
Mark