Co-op Main Quests Broken

So i tried using a character that had quests already completed to play with my wife's new character but quests in act 1 were bugged and you couldnt progress the main quest line together. We had to log to out, go to single player, advance the questline and then log back in as co-op to keep playing. Happened all throughout act 1, havent attempted act 2 yet. I also made a new character and we ran into the same issues, main questline stuck unable to progress. Some examples are the keys in the cemetery wont unlock the gate. Another is Summoned NPC's dont show up. Paths blocked for the new character but the old character can walk through. The symbols on the hooded ones tree are unclickable.