Sorry to necro this thread. Multiple people have listed the actual solution to this issue I will try to make it easier to read.
If you dont have the ability to see a physical quest from Thrall. GO TO either the Stormwind OR Orgrimar Adventure Board. There you should have a quest to fight the burning legion… Accept that one and follow where it takes you and skip the quest in the dialogue while speaking to the NPC the above quest takes you.
Once all that is done. Takes less than 5 minutes to do… You should then be teleported to New Dalaran and the Air Elemental will ask you to follow it. ** While you are there, finish the dalaran mage quest to be able to use your Dal hearth if you ALSO cannot use it ** Go to Thrall and the quests should be available. They were for me after I did what I said above.
Hopefully this helps people who were stuck like I was. Its a quick process. It sucks that you have to do it but it beats not being able to do it at all. Good luck.