For your server to show up in the server list, there is now a requirement to have an ApiKey issued by vankrupt. This is to prevent DOS attacks against the master server
Get the key by going here: https://pavlov-ms.vankrupt.com/servers/v1/key and using your mobile number to get a SMS (note that there have been reported failures of this SMS system for non-US mobiles. In this case DM davevillz your mobile and ask for a key)
Put this key in your Game.ini located in: "/home/container/Pavlov/Saved/Config/LinuxServer/" as follows:
ApiKey="ABC123FALSEKEYDONTUSEME"