Thank you for your help. Running the following:
sudo /etc/NX/nxserver --addtoredis
did the trick. Now I can connect to my physical display again!
Before I did that, I did try to change the DefaultDesktopCommand
as you suggested, but to no avail.
Perhaps the above command will have fixed that too (?). Nevermind though, what I really need is the physical display.
Thanks again.