Red-faced, I'd like to publicly declare that @mike.maxwell was right and I was wrong. I took my interior hue motion sensor outside, right in the sun, and sure enough it registered lux over 10,000 pretty quickly. For any morons like me that follow, both hue sensors (interior and exterior) report illuminance in lux. Any understanding to the contrary is old news and incorrect. Sorry for perpetuating a myth.....
For proof, look at the lux reading below:
