My Pixel 2 XL Screen goes black during phone calls (like it should when I bring it to my ear), but it doesn't ever let me access the screen until the call is hung up by the other person or I press and hold the power button until it does a hard reboot. The phone is completely unresponsive to Fingerprint, volume buttons, google assistant, or power button (unless held for 15-20 seconds). Nothing will wake up the screen.
Pixel 2 XL is updated to Android P with all the latest patches (as recent as July 2019)
No screen protector blocking the Proximity Sensor
Proximity sensor tests shows sensor works to sense something is covering it, but it still shows that it is covered even after the hand is moved away.