Map reset after Arbiter first kill

So i just did Arbiter for the first time finishing up the quest, but after i got him down and got the 2 books and interacted with the fragment that drops down nothing else happened. The dragon came up, talked for like 2 seconds and flew away. I went back to my hideout through portal since there was no other way out, and when i got back every part of the map i explored is now fogged back up.