VL53L0X spurious readings noted when kept on floor

[HarryPotter]

I am using VL53L0X for distance sensing with a PMMA (acrylic) glass cover of 0.6 mm on it at an distance of 0.4 mm. When i keep the sensor on the ground and try to get the distance measurement when there is nothing but the roof in front of the sensor, the sensor gives random sub 100 readings.

I have put the range ignore threshold to 0.0030, i have calibrated the sensor for offset and Xtalk. Still the random behavior is seen.

Any help will be appreciated.

Thank you for your valuable time.