Troubleshooting
The screen is black on lock screen, Netflix, or other media apps​
For privacy, security or copyright protection reasons, apps can prevent its content to be captured. This will result in a black screen in Tango, and there is nothing we can do.
While you can't see the screen content, you can still control the device using mouse and keyboard. For example, you can use keyboard to enter the PIN to unlock the device.
Can't control XiaoMi devices​
In developer options, XiaoMi devices have a USB debugging (Security settings) option. It needs to be enabled for controlling the device.