pThumb image generation from PDFs

I have template which allows me to generate a thumbnail from a PDF using a simple TV.
My code has been in place and working for over a year.
suddenly it's not working. pThumb now only outputs the path of the PDF, rather than generating an image.

This is my code:


I'm not sure if this was caused by an update in pThumb, or an update in ImageMagick, or GhostScript? Or even PHP?

Has anyone encountered a similar issue?
I thought it was to do with migrating to a new server, but it turns out that the old server is doing the same now (hence why in a new thread).

Thank in advance

Andy

I did an experiment by changing &spf to 1, and it created a thumbnail.
It seems as though it doesn’t like the content of certain pages.
&SPF=0 worked originally for all PDFs - so something must have changed with the processing software.
Not sure if that sheds any light?