I had the same issue with an iPhone 7 on which was doing a back case swap. The original phone was badly damaged and the case was bent. I had ordered a new back case and swapped the motherboard and other parts. The touch ID works , but the home button would sometimes multiple-click. After trying different screens, swapping the taptic engine, I put the home button under the scope and found the slightest wear/tear on the cable where it folds in half. I’m guessing that’s what is affecting it.