Forgive me but maybe there is a basic misunderstanding.
I don't know the details of your experiment. I don't know how you organized it. I am talking about JT digital systems in general and how they try to decode a message. I tried and tried again to delete that blessed archive file and the various programs, not only that of K1Jt but also the derivatives, become more "deaf" without that file. It is an experiment that anyone can replicate. And if after deleting that file, disconnect the Internet as well, you will have other surprises.
Lucio, I think you haven't read what I wrote, I do not use wsjt-x or any derivative. Perhaps there is a basic misunderstanding indeed.