Bugged for me too! Even revisited each quest location to make sure I didn’t miss any.
So I folloed AGO’s link, opened up each quest and pasted the print completed command from wowhead for each quest. I was missing 2. I went and did and got credit. They aren’t in a line like most.
Also having this issue! please fix it! ty
This fixed it for me as well. The ! wasn’t above adazius’s head because it was a low level quest at 70.
For those, like me, that didn’t have the problem solved by Adazius’s quest, this one might be your fix. I found Dazakros with 2 quests I hadn’t completed standing at (53, 58). They are the two quests Ago mentioned, “Beaky Reclamation” and “Deluge Dilemma.” I finished these and got my Sojourner achievement.
Ditto. This was my issue too. Thanks for the info!
+1. Thank you!
According to wowhead completion tracker I have all the quests for this done, but I can’t get the achievement still.
thank you i was missing this quest as well
I was missing a different quest. I used BTWQuests addon to find what I needed.
Yes, the quests do not need to be completed in order it seems
Thank you so much! This worked. I went back to that area and somehow hadn’t completed The Bitter End which followed into Life After Life. I completed those and then saw the quest marker for A Better Start. Completed and got achievement. 
if youre still having issues and this didnt work for you, check if you have completed the Little Scales Daycare quests or at least have started them! I was working on them when the broken quest line started working