Grid Export to PDF gives "Error creating PDF file, contact technical support."

I have read the various solutions offered but I can’t get it to work.
HTML, CSS, and Log file are all created in the TMP folder.

LOG file shows :
./wkhtmltopdf-amd64 --page-size Letter --orientation Landscape --outline-depth 0 --header-right “[page]” https://MYWEBSITE/_lib/tmp/sc_v9completed_job_grid_html_ad11ac74ffece31fd48a4d80002032c3.html /home/MYWEBROOT/public_html/_lib/tmp/sc_pdf_20171205074018_77_v9completed_job_grid.pdf I have changed the permissions on the wkhtmltopdf folder to 777, as suggested by someone in the forum, but still doesn’t work.
I have confirmed there is no value in disable_functions in PHP.

This is on a VPS, not a shared hosting environment.
Does anyone have any advice how to get this to work?
Thanks