Exotic Missions

I just started playing again after years of inactivity. This morning I beat heliostat and got the cool axe. I wanted to get more of the (new to me) exotics by playing some of the other missions. I rand through persage and the black garden one multiple times but never got the exotics. I also cannot find any relative info on Google. What am I missing? I only have a few of the old dlcs