After applying the latest firmware upgrade for the Thunderbolt controller (1) Thunderbolt controller DOES NOT appear in device manager, (2) connected Thunderbolt devices do not appear as "connected" in the Thunderbolt software.  My Lenovo Thunderbolt 3 Workstation dock now functions ONLY via USB-C (i.e. network port works, but display port does not).  This firmware update essentially makes my X1 Extreme's Thunderbolt 3 ports function ONLY as USB-C ports.

Since the issue started with an automatic update to the FIRMWARE of the Thunderbolt 3 controller, nothing done with the Operating System can resolve the issue.  I’ve tried restoring to a previous restore point as well as reinstalling the OS.  In both cases, the Thunderbolt controller does not “sense” the connected Thunderbolt device. Since the firmware for the controller has been updated I believe there are only two options (1) replace the hardware or (2) change the firmware for the controller.

I think Lenovo MUST do one of two things:

Option 1: Immediately release an updated version of the Firmware for the Thunderbolt 3 controller that restores functionality.

Option 2: Make available a previous version of the firmware for the Thunderbolt 3 controller so that it can be downgraded (i.e. to version 17.0.0.10).  The readme for this latest update (https://download.lenovo.com/pccbbs/mobiles/n2eti10w.txt) lists previous versions of the firmware, but they are not available from Lenovo’s support site.  

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VERSION INFORMATION

  The following versions have been released to date.

  Build ID Update          Package   NVM   PD          Rev. Issue Date

            Tool            Ver       Image Image 

  -------- --------------  --------  ----- ----------  ---- ----------

  N2ETI10W 17.0.0.12       N2ETG15W  50.00 F407.06.27  01   2020/04/30 ß---- problem update

  N2ETI09W 17.0.0.10       N2ETG15W  50.00 F407.06.27  01   2020/03/17

  N2ETI04W 1.0.12.0        N2ETG10W  36.00 F407.06.17  01   2018/11/08

  N2ETI03W Build_20180516  N2ETG09W  36.01 F407.06.17  01   2018/09/28

I am seeing the same problem. Does not recognize thunderbolt at all, also will not connect to external monitors via USB-c

I have simmilar problem. USBC with external monitor is working. 

HDMI smometimes detect monitor but even when detected there is no signal and only black screen. When I remove hdmi cable from laptop, system still see external monitor. Tested on different cable, monitor but hdmi does not working.

Thunderbolt display port sometimes works, mostly on Ubuntu 19 LTS, on win10 often has error that cant detect usb device but randomly works properly.

Can anyone help?

I test different version of BIOS, drivers, cabels, monitors, reinstal system....

@JimStowe I found the previous version of the firmware N2ETI09W 17.0.0.10, give me an e-mail I will send you it. I dont know why I cant attach file. Unfortunately, it didn't change anything for me :(

@Tardyon, I appreciate the offer.  I also finally located a previous version of the firmware for the Thunderbolt 3 controller.  However, since the application of the latest firmware makes the Thunderbolt 3 controller "disappear" from the device manager, it's not possible to flash it with an earlier version.  I get to the end of the installation and get an error message that essential says, "There's no thunderbolt controller on this system."

I suspect the only fix is going to be a motherboard replacement.

May I ask if Lenovo has solved the problem?   I just found the same issue.   Thunderbolt does not work as I connected it to an external monitor through HDMI on usb-c hub.