Hi Grant, both of the laptops were used in the same room under the same lighting conditions. Like I mentioned it doesn’t actually work completely flawlessly on the Thinkpad (there was a 5 second wait before head position data arrived) after running it. I have not yet witnessed that problem on eye gaze or fixation samples. But other than that it’s been fine on the Thinkpad.
Though yeah it is a bummer that headtracking has stopped working on my Surface Book altogether.