Apparently Adobe's silly DRM:ed PDF:s are causing problems with printing systems here and there. When one of those gets converted to PostScript for printing (by Adobe Reader), it adds some magical tag saying that this document has DRM and should not be converted back to PDF (or similar). Unfortunately it seems that Ghostscript respects this silliness and refuses to convert things for thinlocal.
Created attachment 402 [details]
Created attachment 403 [details]
This was reported on Issue 12426. They provided us with some example documents.
This bug is old. Let's retest if this still is an issue.