Ok, looks like I fixed it.
In function “voucherpress_render_voucher” I changed the font from:
$pdf->SetFont($voucher->font, ”, XX);
to something like this:
$pdf->SetFont(‘freeserif’, ”, XX);
and cyrillic appeared in pdf.
Have the same problem (v.1.4). Cyrillic works fine everywhere except the preview and voucher pdf. Can you point to the code where the voucher is created? Maybe I will be able to fix it.