Today I logged my level 70 toon and I entered a Timewalking dungeon and was given “A burning path through time.” I completed this at level 74 but there was no where to turn it in, not in Tanaris like you could the last 2 weeks and not in Dornogal either. On my wifes toon, she was able to turn in this quest with her level 80 toon in Dornogol while the NPC that had the blue colored question mark above its head didn’t have one for me. I thought, maybe it’s cause I’m not level 80 yet (that hasn’t been an issue, for any of my other toons I leveled) but when stuff doesn’t work the way it should, you start thinking “maybe” it’s me. Anyway I hit level 80 and the quest was there in Dornogal again. Now I have 2 of them on my quest log, 1 completed and 1 saying I need 5 more timewalking dungeons. I submitted this as a bug, and I submitted this as a ticket too! Annoyed because I did the work and I want my loot 
Edit: There is another thread up I found only after I already posted this and the answer is to turn in this lower level timewalking “A burning path through time” it’s in Shattrath City upstairs by the timewalking vendors 
Although since I already hit level 80 I didn’t get the experience and the gear now was only +4 but that’s where the turn in is! For anyone else having the same issue, as me.