Caller ID is not working (Xiaomi Mi3)
Please follow these steps if you are having difficulty enabling caller ID on your Mi3 phone:
Phone settings -> scroll down and select Apps -> Go to “All” Apps or “Downloaded” Apps -> Scroll to the bottom of the screen and select “Eyecon” -> Click to ‘enable floating window’ -> Scroll down to ‘Manage permissions’ -> Make sure that you have enabled “Trust this app” and “Auto-start” -> Select “okay” if you are asked for additional permissions
See here for general Xiaomi solutions.