Dell Thunderbolt Monitor Briefly Detected Then Disappears

[BrianHsu]

When connecting a Dell U2725QE monitor via USB-C (Thunderbolt), the device appears briefly (for 0.5-1 seconds) in the Thunderbolt Control Center, then disappears. The monitor does not display anything. The only time it might work is when connected before boot, but even that succeeds very rarely.

Environment:
- BIOS Version: 01.21.00
- Thunderbolt Controller: Intel Thunderbolt 4 (9A1B)
- OS: Windows 11 Pro 23H2
- Monitor: Dell U2725QE (Thunderbolt 4 capable)

Observed Behavior:
- Thunderbolt Control Center detects the monitor for 0.5-1 seconds, then it disappears.
- The monitor does not activate or receive signal.
- Keeping the monitor plugged in before boot only helps in extremely rare cases.

What I’ve Tried:
- Rolled BIOS back from 01.21.00 to 01.14.00 using official HP tools

- ME and firmware rollback fail with error log "Full Recovery of the Intel Management Engine Firmware failed, unable to find a valid firmware image."

Request:
- Is this a known issue with ZBook G8 and BIOS 01.21.00?
- How can I restore stable Thunderbolt functionality and ensure displays are detected properly?

Thanks for support.

[Vjx]

Hello BrianHsu ,

Thank you for reaching out. Regarding your query on Dell Thunderbolt Monitor Briefly Detected Then Disappears that you’re experiencing.

Appreciate you trying out exhaustive troubleshooting !!!

Kindly review the instructions as below :

-were there any hardware or software changes recently 

- Please test the device with HP monitors

- share more details of the product like serial product numbers or complete model name

- We at HP do not encourage using 3rd party accessories or devices , hardware upgrades unless advised in any form of hp documentation

- Find all relevant guides and drivers from the support page here on best effort basis with the limited details that we have about the device  -

https://support.hp.com/in-en/drivers/hp-zbook-power-15.6-inch-g8-mobile-workstation-pc/2100648425

https://support.hp.com/us-en/help/hp-pc-hardware-diagnostics - this works with HP devices only 

https://support.hp.com/us-en/drivers/hp-thunderbolt-dock/20075223

https://support.hp.com/us-en/document/ish_4140726-4140628-16

This will help us narrow down the cause and suggest the best fix