Short answer: Yes — on many HDR laptops/displays you must lower the panel’s brightness (and/or disable auto/dynamic brightness) to see the gray steps during the Windows HDR calibration tests. At full HDR peak brightness the screen clips to full white and the gray ramp disappears.
Why that happens (brief):
- In HDR the panel/output are allowed to hit a very high peak luminance. A full-frame near-white patch can drive the display into its peak-output mapping so small differences between gray levels become visually identical (all look white).
- Some laptops also use dynamic contrast / ambient-light adaptive brightness which forces full output for a “white” fullscreen pattern.
- The Windows calibration tool assumes you’ll change...