I'm running Workflow Admin Console 11 and Workflow Designer 11 on my Workflow server.

I have a workflow that calls a script that merges multiple PDF files into one PDF file. Recently, the script seemingly hangs (runs for days, instead of seconds/minutes) on some PDF files. In testing, if we take one of the problem PDF files, save it as DOCX, then save it back to PDF, the workflow completes as expected. This led me to think maybe we need a newer of itextsharp.dll (or itext8.dll which supposedly replaces it). I uploaded version 5 of itextsharp.dll and replaced the older version (4) with it in the Workflow folder path. When I look at the references in the Script Editor, it appears that it's still referencing the older version in the Windows GAC:

I tried to add reference to the newer dll that I uploaded to the Workflow path c:\Program Files\Laserfiche\Workflow, but nothing in listed on the server (LFLOW):

I read in other Answers articles that when the workflow runs, it only uses references in the Workflow directory path (is that true?), and you have to register or reference it in the Workflow Admin Console (but where?).