I'm having the same issue, I have 2 accounts, trying to run Ark from my PC via the account that was hosting my dedicated server from my xbox one and I can bring up the dedicated server, but the option to join the server is greyed out and myself or anyone else is unable to join. Also I'm trying to figure out if i need to start the game from my xbox app, my start menu, or what at this point. clarifications are needed on this stuff..