Far Cry 4 Co-OP Joining Problems and Glitches
It seems there is a problem while playing Far Cry 4 Online specially when you are trying to play in co-op mode, most of the players reported a glitch that don't allow them to join other players in the co-op session.
The real problem in Far Cry 4 video game is that other players can join your game but you can't join theirs seems more like a regional problem or a glitch thingy by UBISoft.
The more related errors to this problem is "Lost Connect to Your Partner" and far cry 4 stuck at the Kyrat menu for more than ten minutes.
If you are facing FAR CRY 4 CO-OP Problem the UN-official fix to this problem is to keep on clicking on "Join Coop" till you join.
The second solution is the latest patch available at far cry 4 official website.
Do let me know if you fix the problem by another method, till than i am out.see ya amigo's.