Hi Erich,
Thanks so much for the reply! I bet the "Non-Stop" is the reason.
After upgrading, the debug mode still shows "Non-Stop", but the live view does not work. By following your hints, I changed the debug mode to "All-Stop" and then changed it back to "Non-Stop", suddenly, it works!
If anyone else met the same issue, here is the way to fix it.
Thanks again!
Haizhou