I apologise for resurrecting an old thread, but after doing a google search after finding out that my China map disappeared from my Lumia 1520, I found a reason from mobilegeeks.com (search for 'HERE Maps No Longer Support Hong Kong, Macau & China on Android'). An excerpt from the article:
"China is not currently a primary focus market for HERE. While China – like many other markets – will see a greater role for location services as connectivity becomes more pervasive, the regulatory environment means that we have not been able to apply the same business model in China that we have had success with elsewhere. Chinese rules prevent us as a foreign entity developing and owning the map. As such, the market is not attractive to HERE right now, but we’ll continue to monitor the regulatory developments." - Dr. Sebastian Kurme (Communications Manager, Nokia)
P.S. I apologise for not being able to post a link as my post count is only 3, and I need a post count of 10 to be able to post a link.