Hey so I'm having a similar issue to the PC players. Notably, I literally cannot join any friend groups or invite any successfully.
While reading I've discovered PC players fix this issue by deleting latent beta files, i however have none left on my xbox and cleared my cache twice. I am greatly enjoying the game and would love if only this singular issue were fixed. My ability to connect to multiplayer matches is relatively unhampered, and despite my strict nat type I played fine on the open beta both PC and console versions, my friends all with strict nat can connect to each other without issue.