OK so to answer your question directly, the touch ID not working correctly after LCD replacement. The problem is not in the tough sensor, the problem is in the LCD you replaced it with NOT being an OEM replacement. There are OEM parts out there. OEM stands for parts made to the ORIGINAL EQUIPMENT MANUFACTURER specifications. If the part is not OEM then it may not work with the newest versions of iOS. What you will need is an OEM LCD replacement. If you did purchase an OEM replacement then you may have just gotten a bad LCD. I also want to stress that purchasing an OEM screen does not mean purchasing it from Apple. There are plenty of suppliers selling legitimate parts.