"Join Player" grayed out

When I open the roster and click on the name of a friend, the option to “join player” is always grayed out. Is this working for anyone? Am I missing something?

Also where are the party privacy options (open, friends only, invite only) located??

thx! Really enjoying the latest MCC update, btw.

If your friend is in the player search or in a game, you can not join. Players will not be able to invite you during this time aswell.
In addition, you can not join friends who appear as offline or set their party privacy to “invites only”.
The party privacy options can be changed, when you press x, and go to “my game session”, wich is on top of your gamertag/lobby.

I do not know if there are any more factors involved. I have summarized this constellation of experience, so further opinions would be appropriate.
greetings