Studio Display XDR dims when MacBook Pro lid is closed for editing

Studio Display XDR Screen Dims Entirely When Entering Edit Mode and Playing Videos on M4 Pro MacBook Pro with Lid Closed

Description:

When using an M4 Pro MacBook Pro with the lid closed and Studio Display XDR as the sole external display, the entire screen automatically dims in the following scenarios:

1. When entering edit mode in Lightroom Classic or Nikon NX Studio
2. When playing videos with third-party media players

Upon entering edit mode or starting video playback, the entire display's brightness decreases significantly.

System Configuration:

• MacBook Pro M4 Pro
• Display: Studio Display XDR
• macOS Versions: Problem occurs on both macOS 26 and macOS 27
• Usage: MacBook lid closed, XDR as the sole display
• Software: Lightroom Classic (latest), Nikon NX Studio (latest), multiple third-party video players

Problem Details:

1. Photo Editing Scenario: When editing RAW photos in Lightroom Classic or Nikon NX Studio, the entire screen brightness decreases, disrupting the entire workflow
2. Video Playback Scenario (tested with multiple third-party players):

• When playing SDR video, the entire screen returns to normal brightness after approximately 15 seconds
• When playing HDR video, the entire screen remains dimmed and does not recover

Scenarios That Do NOT Trigger the Problem:

• Previewing RAW files in Finder does not cause screen dimming
• Playing videos in Finder does not cause screen dimming

Critical Finding - Workaround: When simultaneously activating both Studio Display XDR and MacBook Pro's internal display (opening the MacBook lid), the dimming issue immediately disappears. When both screens are active, XDR maintains normal brightness

Attempted Solutions (All Unsuccessful):

• Disabling "Auto-adjust Brightness" in System Settings
• Disabling True Tone
• Disabling "Adaptive Brightness" on Studio Display XDR
• Updating to the latest macOS and XDR firmware

Expected Behavior:

Screen brightness should remain stable when entering photo editing software or playing videos. Editing non-HDR RAW files and playing SDR videos should not cause screen dimming.

Additional Observations:

The problem occurs on both macOS 26 and 27. The critical finding is: the problem only occurs in single-display XDR mode; it immediately disappears when MacBook's internal display is simultaneously activated. This strongly suggests the issue is related to macOS's color management logic in single-display configurations. The system may be applying more aggressive color space detection on XDR in single-display scenarios, incorrectly triggering HDR/wide-gamut adaptation mode. The fact that SDR video brightness recovers after 15 seconds further indicates this is a system-level color space detection and hardware adaptation issue, not merely a software settings issue. The problem reproduces across multiple third-party video players, confirming this is a system-level problem rather than application-specific.