X670E Taichi Carrara TB/USB4 enumeration

**Subject: Rear Thunderbolt/USB4 ports fail to enumerate devices ??ASRock X670E Taichi Carrara**

**TLDR:** Rear USB4/Thunderbolt ports on my Taichi Carrara won't reliably enumerate any device, dock, webcam, or plain external SSD, even though every individual device is confirmed working fine elsewhere. Points to a port or controller level fault rather than a driver or device compatibility issue. Anyone seen this or found a working fix?

**System:** Ryzen 9 7950X3D, ASRock X670E Taichi Carrara, PNY RTX 5080, G.Skill Flare X5 32GB DDR5 6000MHz, Samsung 980 Pro 1TB, Seasonic Focus GX-1000, Windows 11 Pro (clean install)

**Symptoms:** Rear Thunderbolt/USB4 ports fail to properly detect multiple, unrelated devices:
- Anker Prime TB5 dock: Code 10 on Intel USB 3.10 eXtensible Host Controller in Device Manager. Thunderbolt Control Center shows the controller itself as healthy (TB4, chip 1137, PCIe tunneling enabled, firmware v35.0), but it never lists any attached devices.
- Samsung T7 Shield SSD, connected directly with no dock or hub involved: powers on briefly then drops. Confirmed healthy, works perfectly on a different laptop via direct connection.
- Logitech Brio webcam via Logi Dock: only enumerates reliably at USB 2.0 speeds (high-speed USB 3.0 mode off); fails to be detected at USB 3.0 speeds.
- Anker dock's built-in Ethernet port: never detected in Device Manager at all when connected through the rear port.

**Troubleshooting completed:**
- Full BIOS update to latest version
- Reinstalled AMD chipset drivers
- Uninstalled/reinstalled Intel Thunderbolt driver via Intel Driver & Support Assistant
- Disabled USB selective suspend (globally and per-device for the Thunderbolt controller + all Generic USB Hub entries)
- Confirmed the separate Code 28 "Unknown device" is harmless (ACPI\AMDI0204, an AMD component), unrelated to this issue
- Confirmed the dock is fully functional when tested on two separate Macs (M3 Pro and M5 Pro), and a Lenovo Legion 9i ruling out the dock itself
- Clean Windows 11 install already done prior to this troubleshooting

I already have a support ticket open with ASRock, yet to receive a reply though, but wanted to check if anyone else on the Taichi Carrara has run into this specific pattern, since it doesn't seem tied to any one device.