Trying to edit my /etc/hosts file to get a pre-launch site showing up properly in my browser, and it’s not working. I’ve done this dozens of times in the past, but not since the Catalina upgrade.
As @ismh is saying, you might want to verify that your new entries to the file has been successfully written to disk, using the cat command, but you probably did that already…
Still not on Catalina myself, so I can’t really test anything on my end yet.