Received the Thunderbolt 3 dock today, though the display works fine, the dock/laptop won't recognize any external USB devices such as mouse. keyboard, webcam, etc. I tried installing the latest drivers to no avail, from:

https://support.lenovo.com/us/en/solutions/acc100356

Anyone else havign this issue?

Yes, I am having th same issue on my X1 Carben Gen 5.  I cannot get my keyboard or mouse to work on any of the USB ports.

May not be a solution, but a tip nevertheless:

Had the same problem upon booting X1 Carbon. After first time login, a prompt from an Intel program called "Thunderbolt Software" popped up and asked to be run as administrator. Pressing "OK" at this prompt launched the Intel software where I could accept the Thunderbolt docking as an attached device. After this, I could attach mouse, keyboard and other peripherals.

Search for "Thunderbolt" after first boot in Windows 10. If nothing comes up, try to download "Thunderbolt Software" from Intel.

Hey thanks - this solved my issue with it.  Not OP, but had a similar issue.

Also made some changes to the BIOS side according to this lenovo support page: https://support.lenovo.com/ca/en/solutions/ht503639 "How to configure the Thunderbolt 3 Security Level in BIOS Setup for Microsoft Windows operating system - ThinkPad".  I just set the security level to 'no security' for now until I could get it working.

Having same issue: X1 Carbon Thunderbolt 3 Dock Not Recognizing USB Devices (mouse, keyboard etc..) after going to sleep, upon waking up - not able to get Mouse & Keyboard to wake up unless we reboot.

Using Win7-64bit on X1C5, Thunderbolt 3.

Tried BIOS Settings / for Thunderbolt 3 = set the security level to 'no security'. - Not successful.

Any thoughts?

Unfortunately no progress on my end, the dock still doesn't recognize USB peripherals, Lenovo has just ignored the issue...

Thanks to Lenovo Rep - Andy A. who took time to visit us in (Cleveland, OH) today from Lenovo (Columbus, OH) - Much appriciated!

There are several things to look at, that can possibly fix the issue:

• If the RED LED on the top or the Docks power button is going to sleep, it flashes very fast, then slows down to a periodic glow – this means that the unit is entering SLEEP MODE when its flashing rapidly.  Likewise, to remove from SLEEP MODE, you tap the power button on Dock or Laptop 1x to remove from SLEEP MODE. It’s possible you just need to tap the power button 1x to wake up the PC.

• When a Laptop is attached to a NEW Dock for the first time you will see a pop-up stating "NEW THUNDERBOLT devices have been attached" - click OK, Yes, Select "ALWAYS CONNECT".

• X1C5/Thunderbolt 3 dock – we have seen where two separate devices using two separate USB transceivers can slow response.  If possible try a Unified Transceiver (single USB Transceiver) Using this type of device allows 1 transceiver for purpose of using both devices such as a mouse and keyboard vs. having two separate transceivers – one for a mouse, one for a keyboard) – this speeds up reaction time apparently (Win7 more noticable due to slow response, Win10 less noticable due to faster response). 

• Check  BIOS > Config > Thunderbolt 3 Menu should be set like this (all default):
• Wake by Thunderbolt 3 = Enabled
• Security Level = User Authority
• Support in Preboot Environment:
  • Thunderbolt Device = Disabled
  • USB Device = Disabled
    • I had previously had ENABLED both PRE-BOOT Environment as an attempt to solve the issue – lesson: (Leave it as Default / Disabled).

(Verify BIOS, Thunderbolt firmware and software are updated on X1C5 and older models):

• Update BIOS…
• Update Thunderbolt Firmware…
• Update Thunderbolt Software…

X1C4/Dock1+ -  Keyboard and mouse seemed to not wake up after sleep.

• Run System Update from https://pcsupport.lenovo.com  (where the system detects what needs updated vs. what’s installed) the Hotkey update was installed and proved to be the fix or solution in this case.

X1C5 / Thunderbolt 3 Dock – ALWAYS USE a 135w power supply and also when a Laptop is attached to a NEW or different Dock for the first time you will see a pop-up stating "NEW THUNDERBOLT devices have been attached" - click OK, Yes, Select "ALWAYS CONNECT".

Also see Lenovo's T-shooting Guide:

• https://download.lenovo.com/pccbbs/options_iso/tp_thunderbolt3dock_troubleshooting.pdf

The BIOS config you mentioned for a Carbon X1 5th Gen DOES NOT ALLOW 512MB of Dedicated Video Memory.

To enable this amount of memory, the TB3 security needs to be on for "USB and DisplayPort"

With this enabled, the TB 3 DOCK USB ports and Ethernet DO NOT WORK. 

LENOVO: Please Respond.  Does the TB3 Dock WORK AS PROMISED with a Carbon X1 5th Gen, running 512MB of dedicated video memory?  EVERY SINGLE PORT must work.  Otherwise it's a useless "dock".