Can't Create Party with Friend

Has anyone found a reliable fix do this problem? We are in party chat on the PSN, both can connect to BO3, and have no problem playing multiplayer games. It just tells us "Lobby not joinable". We can even join each other's games that are already in session (but no guarantee we'll be on the same team).

Is this just a 3arc/BO3 issue? I don't see how it could be our NAT, router, or whatever since we can both play the game and party chat on psn with no problem. He got the game in early January, and we didn't have any problems until maybe a week ago.

It only works if we both join our third friend's party, but he's hardly on.

Things we're tried:

• Party up in a custom game
• Reset routers
• Cleared BO3 cache
• Reset console

Any tips or help would be greatly appreciated. Thank you.