Further to that I neglected to mention that the critical error is triggered when the download button is clicked on which is when the formk2PDF supplies the created PDF. Download URL is http://teachback.draftsite.net.au/wp-admin/admin-ajax.php?action=wpfx_generate&form=8zkyn&dataset=13061&layout=16&download=auto&key=1c1de20cc445bdf68194dcc1a0d29bbb