@Larisa I have set up an Obelisk in my house two weeks ago and it also did not work. Then, after reading this, I remembered that I had two "Heart of Earth" in the bag. After switching them the tip suddenly started bobbing and doubleclicking worked fine.
Maybe you have mixed parts from different sets? I know that quested more parts with another account after finishing the set, because I wanted a "Tongue of Flames" for deco purposes. I did not switch these to see if it stops working again, but my guess is that you can't mix pieces you got with different accounts.
Maybe someone else can try to reproduce this? And I hope you find your fitting pieces to set it up again.
