Error exporting sdlxliffs back to pdfs in Studio 2017

I received a Studio project consisting of sdlxliffs that were created from pdfs with Studio 2017 by my client. After translating these sdlxliffs, I exported them back to pdfs, but these cannot be read. Foxit Reader throws the error 'format error: not a PDF or corrupted.'

How can I find out what goes wrong? And how can I solve it? I'm using build 14.0.4760.1 and Win 7 Pro 64 NL.

Regards,

Heijo