Mac: MacBook Pro with M4 Pro
macOS: 27.2 (Build 26B123)
External display: Princeton (identified as HTBTF-24W; EDID reports manufacture year 2011)
Before updating to macOS 27.2, the same Mac, HDMI cable, and display worked normally at 1920 × 1080 @ 60Hz.
After the update, when connected directly to the Mac's built-in HDMI port, the display was detected as a generic "Display" and operated at 1280 × 720 @ 50Hz.
When I enabled "Show all resolutions," 1920 × 1080 was listed as an available option. However, the "Default" option was missing. Selecting 1920 × 1080 did not apply the setting; it reverted to 1280 × 720. The monitor's OSD continued to show 1280 × 720 @ 50Hz.
I tried the following without success:
- Disconnecting and reconnecting the HDMI cable.
- Fully powering off the monitor, including unplugging its power cable.
- Starting the Mac in Safe Mode.
- Connecting the monitor before starting the Mac.
- Starting the Mac with the HDMI cable disconnected, then connecting it after startup.
What eventually restored normal operation:
I connected the display through an Apple USB-C Digital AV Multiport Adapter, using one of the Mac's Thunderbolt ports. The display was recognized correctly through the adapter.
I then disconnected the adapter and connected the same HDMI cable directly to the Mac's built-in HDMI port again.
After this, the display was correctly identified as "HTBTF-24W" and operated at 1920 × 1080 @ 60Hz.
The normal resolution list now shows:
- 1920 × 1080 (Default)
- 1600 × 900
- 1280 × 720
- 960 × 540
Enabling "Show all resolutions" reveals additional options.
The correct display identification and resolution have persisted, including after restarting the Mac.
I have not been able to reproduce the original issue since it was resolved, so I cannot confirm whether this sequence is a reliable workaround.
Could this be related to HDMI hot-plug detection, EDID handling, display mode initialization, or any other known issue in macOS 27.2?
[Edited by Moderator]
