Hello there,
So I’m a new (technically returning) player and I was going through Kul Tiras. I know that the leveling zones can be done in any order, but when I got to the map I could only see the quest for the bottom right landmass. I thought maybe I was under leveled and finished it. I came back after finishing and now can’t access the two other quest chains. There is still a question mark above this map, indicating quests to be taken.
As such, I can’t continue the Kultiras quest chain.
I have the same Issue, but instead of only being able to do drustvar, I can only do the boralus harbor Quest Line. I also thought that might be that im underlevel to do the quest, but not sure. Im lvl 25 on this character.
I’m not certain why you have the option to select a new area, Teneth, it looks like you are only part way through Tiragarde Sound. You abandoned one of the quests “An Overrun Mine” from Junior Minor Joe, which should allow you to continue. Once you have completed that area, then you should be able to pick the next one.
Once an area is started, it must be completed before you’ll be able to select a new one. Skyier, you are still working through the Tiragarde Sound questlines. You have A Letter to the League in your quest log, continue with those.
If you look at the comments section at this page, it will give you an outline of which quests you should complete.
I want to hop in here because i’ve experienced this issue on 3 different characters questing through Kul’Tiras. I completed Tiragarde Sound completely (all chapters completed) and upon returning to the scouting map I couldn’t select the next questline, even though the scouting map still had an exclamation point over top of it.
the scouting map wont work for me either it says i have a quest to pick up but the map is blank tiragrade sound storyline says its done
For BFA content there is a level requirement to get a new zone to quest in. Try getting to 25 if you have completed the Tiragarde Sound quests.
ty that worked it works now 
As Jetsum mentioned, Drustvar should open up at level 25, Stormsong Valley is 35 I believe.
There should be a fairly sizable number of quests still in Tiragarde Sound, you may check out one of the other side quests there.
You’ll find one of the posters on Wowhead listed in the comments here:
https://www.wowhead.com/achievement=12473/a-sound-plan#comments