This problem can occur if your device's motion sensor is uncalibrated.
To correct the problem, run the "Calibration guide" in Horizon's settings. Go to Horizon's settings and tap "Sensor calibration" to enable the sensor correction and complete the calibration guide.
Perform the calibration as shown in the following video:
After some time, your sensor may change and another calibration may be required. Just tap "Calibration guide" to perform a new calibration.