Blocking chinese market cameras from working on non-chinese-market NVRs is certainly intentional on Dahua's part, but I'm pretty sure it's for marketing and sales purposes. Contrary to other opinions, my observation is that the chinese market cameras (the ones I have at least) are every bit as functional, capable, and reliable as their international counterparts that use the same image sensor. They can also be had for about half the price of their international counterparts, and I think that became too well known and was cutting into dahua's revenue. There's an ID somewhere in the camera's PROM that says what market it's for, and that's what stops international market camera firmware from running on the chinese market cameras. Going back a couple of years, the sellers of the chinese market cameras hacked the chinese market firmware's UI to use english. Thanks to the work of a clever forum member I've been able to load my chinese market cameras with international market firmware that ignores the camera's region ID. I'm suspecting that some of the sellers of chinese market cameras have picked up this same firmware.
The question I'd like answered is if the NVR with newer firmware would reject my chinese market cameras running international market firmware. I haven't been willing to upgrade the NVR's firmware to find out because I possibly wouldn't be able to go back. To answer this for myself I'd need to find an NVR with the camera-rejecting firmware and try one of my cameras on it.