I sent an email to DVDFab and received a reply very quickly.
I was told to completely remove the older version, clean out any remaining files, and install 184.108.40.206. beta, using run as administrator both for the install and to run it.
That solved the problem and the screensaver now resumes after exiting DVDFab.
It was great to get very quick expert help right from the developer. Makes me a happy user.
(But I still like the look and feel of version 8 a lot better than the new 9.)