MacBook Pro 2024 clamshell mode fix for triple monitor dock:
Enable “Prevent automatic sleeping on power adapter when the display is off” in System Settings > Energy Saver. Without this, macOS sleeps when the lid closes and the dock connection drops before external displays can take over.
Known Sequoia 15.4 bug may break clamshell mode even with correct settings. Workarounds: Amphetamine app or caffeinate terminal command.