Intermittent boot failure: PA14250 + SD25TB4 – suspected Lunar Lake Thunderbolt PCIe issue

I am experiencing an intermittent cold-boot failure on my Dell Pro 14 Premium PA14250 (Core Ultra 7 268V, BIOS 2.11.1) when connected to a Dell SD25TB4 dock (firmware 01.01.10.01). This occurs approximately three times per week.

SYMPTOM
On cold boot with the dock connected, Windows hangs before the login screen. Disconnecting the Thunderbolt cable and restarting always resolves it immediately.

SETUP
Three Dell P2725QE 4K displays (2× DisplayPort, 1× HDMI 2.1), keyboard, mouse, webcam, and audio on the dock. No external storage.

TROUBLESHOOTING
All drivers, firmware, and BIOS confirmed current via Dell Command Update and SupportAssist. F12 diagnostics: no errors. Event Viewer shows no Thunderbolt, USBXHCI, or ndis errors preceding the hang. No Thunderbolt Operational log exists on this system, and no Thunderbolt Security option exists in BIOS — both consistent with Lunar Lake's integrated controller architecture.

SUSPECTED CAUSE
This appears to be a known Thunderbolt 4 PCIe initialisation issue on Intel Lunar Lake (Core Ultra 200V). Identical symptoms are reported by other 258V/268V users on Intel Community forums, where Intel has directed affected users to their system manufacturer for a BIOS-level fix.

This issue also appears related to two existing threads in this forum:
• PA14250 + SD25TB4 Ethernet problems, which documents Thunderbolt PCIe instability on this exact laptop/dock combination: https://www.dell.com/community/en/conversations/dell-pro-laptop-computers/pro-14-premium-pa14250-sd25tb4-ethernet-problems/689aed19c3c73313956f339c

• SD25TB4 display issues with external monitors (dock firmware 01.01.11.01), where multiple users report intermittent boot failures with mixed display connection types: https://www.dell.com/community/en/conversations/dell-laptop-computers/dell-pro-thunderbolt-4-smart-dock-sd25tb4-display-issues-with-external-monitors/697c7682eaa5155846dedfd4

REQUEST
Can Dell please confirm whether this is a known issue for the PA14250 + SD25TB4 on Lunar Lake, and whether a BIOS fix is planned?