I just did the replacement screen (LCD only) on a 2018 model a1989. Everything works perfectly and the reason for that is probably because I kept everything original and replaced just the LCD. I’ve heard rumors about the T2 chip causing issues for repair and most likely that is your problem. The only way to keep True Tone would be to keep the front camera flex (most likely this is where it’s paired). One way to test this and confirm would be if you still had your original LCD assembly and you can just plug in the front camera flex which is the connector closest to the LCD connector on the LCD board. There should be a somewhere that says SV_CAM (on mine it also says J0802) Plug it in, boot up and see if everything is working perfectly afterwards. Good luck