I can usually invite other players, although I run into issues quite often, but I can't invite a specific friend. Both of us have green NATs, but his NAT has turned orange on occasions. He keeps appearing offline or away when he's online. The weirdest part is that his status often gets changed depending on if I'm look at it from the friends list or if I'm chatting with him. Even when it shows that he is online, he doesn't get notifications from my invites and vice-versa. We tried resetting ubisoft connect, internet routers, our pcs and everything else we could think of. We tried using logmein hamachi. Tried adding him to a group and inviting him this way but it doesn't let either of us create a group.
TL;DR: I can't invite my friend and none of the common solutions seem to work
Please help