Yes, based on what I can find, the Haswell UX303LA has about 61% sRGB coverage so it sounds likely to be a 6-bit (AKA 18-bit) panel, which makes it sound even more likely that comment #5 is the cause of the problem.
Yes, based on what I can find, the Haswell UX303LA has about 61% sRGB coverage so it sounds likely to be a 6-bit (AKA 18-bit) panel, which makes it sound even more likely that comment #5 is the cause of the problem.