VL53L1X rangefinder stops at 20-24cm

Good evening. I have a vl53L1X connected to a holybro px4 running ArduCopter 4.3. It is installed according to the doc pages, and I can see it transmitting through the MavLink inspector on QGC. It consistently functions perfectly from 0-20cm, then between 20-24cm it just shuts off. The highest reading I’ve been able to get is 23 cm. But if I rapidly raise the drone, it will shut of earlier. I’ve tried several sensors, and they all have the same behaviour. Correct numbers resume when the drone os lowered back under the 24cm range. Tried different surfaces too. I’m wondering if there is some magic setting or something that is turning it off. I’d like it to assist with low altitude holds under the spec range of 360cm. But 20 is a little two low to be useful. Any suggestions? Thank you.

Indoors or outdoors?

Indoors. Right now, just on the bench.