So I did the Man who Cried Wolf quest and Elisif told me to buy the house.

I bought the house. I also have "Wolf Queen Awakened" quest active (Falk's courier found me about five minutes after I finished Man who Cried Wolf).

After I bought the house (and tricked it out to the max), there's still no prompt for me to become thane. Elisif does not have the dialog option. Do I have to finish the Wolf Queen Awakened first?

Have you assisted five citizens ?

I have, but I don't have that objective yet. Elisif says after the "place the horn blah blah" quest: now you can take the next step towards being a thane, buy the house in solitude. Talk to falk when you have the funds.

I talked to falk and bought the house and... nothing.