TouchID intermittent after screen replacement.

I recently replaced my cracked screen, moving the original home button from my old screen.

TouchID ever since works intermittently. One minute it will be working and the next it won't. I've noticed that if I lay the phone flat on a table, face down, and knock on the back a few times, most of the time TouchID starts working again until the phone is jostled around.

The button is properly seated, and the connector appears properly seated, the shield behind the home button is properly tightened but not too tight, and the flex cable appears undamaged. Powering on and off seems to have no effect.

Can anyone recommend what to look at next?