You would think that the missile fired over Japan would have been enough to trigger hell fire.

The issue is that the Chinese hate the Japanese. There is nothing that the average Chinese citizen would like more than to see Japan wiped off of the face of the earth. 

Regardless, any potential solution, military or diplomatic will involve the complete cooperation of the Jinping regime. That will not be coming any time soon. 

China's goal is world domination and they will continue to play their game with North Korea toward that end.