Silent Install hanging until shutdown for "unresponsiveness"

I’m trying to run the installer for PACE’s iLok License Manager tools.
I’ve created an .iss file for the installer, and have run it with the flags /S /f1[.iss location], as well as with /V"/qn", and no matter what I do, the session will just sit after the command for 10 minutes until the session automatically closes.

It’s an Install Shield based installer that doesn’t seem to have an .msi that I can reasonably extract. The one I’ve found after beginning to run the original installer refuses to run.

Any help regarding this would be great!