macOS 15.4 Broke Thunderbolt 3 to Dual DisplayPort Adapter

Docks, Hubs, Display Adapters
1

Since upgrading to macOS 15.4, my Thunderbolt 3 to Dual DisplayPort adapter (TB32DP14) no longer works properly with my HP Z27 5K monitor. The monitor requires two DisplayPort connections to run at its full 5120 x 2880 resolution, but now macOS only detects it at 1920 x 1080. WIth the previous macOS version everything was working normally.

It seems like macOS isn’t recognizing the correct resolution anymore.

Is anyone else experiencing this? Any workarounds or fixes?

Thanks!

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2

Hello @timomeinen,

Thank you for inquiring about the TB32DP14 hear on the StarTech.com community.

We can will do our best to look into the resolution issues experienced after the macOS update.

The resolution issues are an unexpected result after the operating system upgrade. There are a few things that I can think of to see if we can be sure that the issue is isolated.

  1. If you have not already done so, try disconnecting the TB32DP14 and restart the Apple computer then reconnect it again after the restart.
  2. Did anything else change with the Apple M1 Pro system, the TB32DP14 or the HP Z27 5K monitor when the upgrade occurred?
  3. Were there any errors or warnings during the upgrade?
  4. Do you have another Thunderbolt enabled computer that can be tested with the TB32DP14?
  5. Can you try testing with different DisplayPort cables between the TB32DP14 and the HP Z27 5K?

Please let us know if these ideas help to better understand what is occurring. It may also be worth reviewing the settings on the monitor itself to see if there are any options there which could help improve performance.

Sincerely,

@DavidF

3

@DavidF Thank you for the support. Happy to help finding the issue.

  1. Reconnected, Rebooted, Removed display plist files, tested all different ports, nothing helps.
  2. Nothing changed, beside the macOS udpate to 15.4. After installing and rebooting the TB32DP14 was not working correctly anymore. macOS 15.4 shows only Full-HD resolution with 2 DP cables connected. Connecting only 1 cable it shows 4K. It is even possible to attach two displays to the adapter having 4K each. But the 5K display with dual DP cables does not work anymore.
  3. Update was successful.
  4. Yes, on my other MacBook Pro with macOS 15.3 the adapter runs perfectyl with the 5K display. See screenshot.
  5. Used two new DP cables but the situation is the same. Connector runs on 15.3 but not on 15.4.

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4

Hello @timomeinen,

Thank you for confirming those reboot steps, and it is very helpful to know that another MacBook Pro running 15.3 continues to work fine.

After taking a few moments to review more about the monitor, the HP support documents did not seem to have any additional clues so I have no suggestions there, for now.

I have inquired with my team for more information. If they have more questions, would it be okay to email you at the address you used to sign up for the StarTech.com community?

Sincerely,

@DavidF

5

@DavidF Of course! I appreciate any help to get my setup working again. Thanks.

6

It is weird. When connecting the display to the old MacBook it switches to 5K every time. When putting the adapter then into the new MacBook the 5K is available, too! But only until next sleep or reboot and only if attached to the old MacBook prior:

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Putting to sleep and wake up again:

Displays:
Farb-LCD:
Displaytyp: Integriertes Liquid Retina XDR-Display
Auflösung: 3456 x 2234 Retina
Hauptdisplay: Ja
Synchronisierung: Aus
Eingeschaltet: Ja
Helligkeit automatisch anpassen: Ja
Verbindungstyp: Intern
HP Z27q:
Auflösung: 1920 x 1080 (1080p FHD - Full High Definition)
UI sieht aus wie: 1920 x 1080 @ 60.00Hz
Synchronisierung: Aus
Eingeschaltet: Ja
Rotation: Unterstützt

7

Hello @timomeinen,

Thank you for sharing the results of your further testing. This is a curious result and might indicate some sort of issue with the monitor and the operating system specifically and not necessarily the TB32DP14. However, we would like to try our best to ensure we can isolate and if possible resolve this issue.

I have also inquired with my colleagues to see if this kind of things has come up before. We will reach out to you directly by email if we need more specific details.

Sincerely,

@DavidF