We had a strange bug in OC 3.x! When adding a PDF link outside of the OC files structure on the same domain name?!
mod_sec = nothing in my log’s,
.htaccess NO LUCK HERE!
Just call your pdf file(s), https / http ,.. link inside your image directory structure ! ,,… ,, just create the OC directory “/image/catalog/terms (Or any name), use filezilla to upload your PDF file.
The bottom line is that you cannot call a non-OC directory, Ex,.: public_html/yournamehere/download/
must be located inside the OC structure: