I have no idea how to send the Direct Connect ID for players as you don't have that option any more, so that did not work either and I guess that is not how you should start a campaign anyway but from the lobby.
If you started a new campaign in Character Creation phase you can press ESC and select connectivity menu. There you will be able to see direct connect checkbox - if its not checked - check it and you will see a button allowing you to copy your direct ID to clipboard.
Well it worked for Hungry journey but not the campaigns with any addons.
Can you guys give a list of mods you have installed for the game? I mean not just for gm campaign - but what mods are you using for whole game? Does your clients use same mods list? Or they have different list?