I am getting only one monitor via my caldigit ts3 plus dock (and charging as well); The dock is connected to the Thunderbolt 3 connection on the laptop. The dock working perfectly on a Macbook Pro that I have as well.
Any thoughts on how to get both screens shown will be welcome.
Your Thinkpad T14 uses the 15BF Thunderbolt Controller / Intel JHL6240 Thunderbolt 3 Controller. It only supports 2 lanes instead of 4 lanes that are needed to control two external screens.
The weird thing: If you try another dock like the Lenovo Dock Gen 2 it will work with two external monitors. I think Lenovo uses some special techniques like Multi Stream Tansport (MST), Displaylink etc.
But if you are now considering switching to the official Lenovo dock, please wait, because two external monitors in extended mode won't work with your MacBook Pro as shown in this video.
To solve the problem, I suggest buying an HDMI/DP to USB-C adapter. Now you have got two cables:
With this setup you can't make your one-cable-dream come true, but you are able to use the CalDigit TS3+ dock on your MacBook Pro and Lenovo Thinkpad T14 with two external monitors.
