@AndyTJ I disabled my firewall and tested and still had the dreaded login window reappear.
Even after your settings in preference.

It is good that it somehow works for you.

By blocking outgoing TCP port 443 on the two QB executables we find that QB does not ask to log in to an Intuit account anymore. 

We do not want our local files calling home to Intuit. My data is safe on my computer. I can log in locally, but do not want or need an Intuit account and login to keep my data safe (from myself????)

As for me, this workaround works. I can still install program updates if needed, either automatically, or manually via the menu item under Help.