Dual DP Monitors not working together

I have a Lenovo Thinkpad L15 Gen 2 connected via the supplied Thunderbolt 4 cable to the TBT4-UDZ dock. I want to connect both of my Samsung G55C QHD monitors to the dock with the standard DP cable provided with the monitors.
When I connect the first monitor to “Group 1” DP, it works fine.
When I connect the second monitor to “Group 2” DP, my laptop recognizes there are two monitors. But I get to display the signal to the second monitor.
If I remove the “Group 2” DP cable and connect my second monitor via HDMI to “Group 1” it works fine.
What is the reason I can’t run both displays of DP ports?

Hi Tomas,

Thank you for posting! We are sorry things are not working fully as expected while using your TBT4-UDZ docking station, and we would be happy to help.

Based on your description of the behavior, our next step is to get some additional information.

Can you please send an email to our direct support email address → support@plugable.com with ‘For ticket #- 435423’ in the subject line that contains the following information?:

  1. The Amazon Order ID number for your TBT4-UDZ purchase

For your reference, that information is typically available here → https://amazon.com/orders

  1. While the TBT4-UDZ is connected to your Lenovo laptop and both Samsung displays are connected to the TBT4-UDZ via the DisplayPort connections (even if not working as expected), the output of our diagnostic utility PlugDebug → https://plugable.com/pages/plugdebug

That information will help us to determine the next steps.

*** Please do NOT post the information we requested above here in our public forum (it contains personally identifiable information) ***

Apologies for the frustration, and thank you for giving us the chance to help!

Plugable Technologies