Meural Canvas Ambient Light Sensor doesn’t work

The ambient light sensor on my meural canvas doesn’t seem to work. I have made sure that “auto adjust brightness” is toggled in the app. I have tried adjusting the sensitivity setting. No matter what I do, the “light sensor” reading is zero when I check the canvas info. It is a new unit (purchased in May from Adorama, but it was only shipped at the end of July). Suggestions?