So my upgrade from my i1 display 2 to i1 display pro loses this feature for some reason... good grief!
I don't recall the original instrument being able to measure ambient light other than for the purpose of either giving you the incorrect starting point for calibration targets (you'd put the instrument under the ambient light near the display) OR for the ambient light compensation which is also worthless. When I mention measuring using the i1Pro Spectrophotometer, it's providing spectral data and other functionality in the old i1Share software. Again, I don't recall the Colorimeter having those capabilities.
Just what are you trying to measure in terms of ambient light and why?