Did you give the dragon of wood some time to finish his speech, until the big window pops up with what to do next?
If you just tap on him and then leave, it is sometimes not enough.
I would say you now have to start with the dragon of Earth quests, but your screenshot shows that your game has not accepted the talk of the previous dragon of wood as finished.
If you give him time and that doesn’t help, please restart your game and see if that helps.
For the next quest you then have to visit the city Digjong to talk to the monk of the earth.
If you did all that, checked Happy’s links and still can’t proceed, you can contact pixel support to see if it is indeed a bug. Usually it isn’t, but you never know 😉
Help with that is here
It would be nice if you could report back if you could solve it and how. 👍