How to reproduce:
1. Download the attached project
2. Build and run on Motorola Moto G4
3. Move device and check logcat for returned values
Result: it gives zero values for Input.gyro.attitude

Reproducible: 5.3.7p3, 5.4.4p1, 5.5.1p1, 5.6.0b5

Note: I have also used Sensor Kinetics application to check if gyroscope works (User showed it in video)

DUT(reproduced):
Motorola Moto G (4) , Qualcomm Snapdragon 617, Adreno 405, OS 6.0.1

DUT(didn't reproduce):
Samsung Galaxy S7 [SM-G930V],Qualcomm Snapdragon 820, Adreno 530, OS 6.0.1
LG G5 [LG-H850], Qualcomm Snapdragon 820, Adreno 530, OS 6.0.1
Xiaomi Mi 4i , Qualcomm Snapdragon 615, Adreno 405, OS 5.0.2

Won't Fix: We cannot measure the attitude of this device because COMPASS and ROTATION_VECTOR sensors are missing.