PDFCreator seems to behave differently when the printjob is started by an interactive logged on user as opposed to being started by a service running under the very same user.
The interactive user spools to appdata/local/temp/1/PDFCreator/spool. The files are immediatly collected and a pdf in the correct location is created. A logfile is created in appdata/local/pdfcreator/pdfcreator.log.
The same user as a service spools to appdata/local/temp/PDFCreator/spool. The files just lie around there forever, and nothing happens, no logfile is created.
PDFCreator can't run in session 0, so it needs a user session it can run in.
Only PDFCreator Server doesn't require a logged on user: https://www.pdfforge.org/pdfcreator-server
Well, this type of usage was never officially supported and has always required some kind of work around or logged on user, it might be possible to somehow also make it work with the new version, but is untested and might not work at all.