Thank you for letting me know the update to DisplayLink Manager 1.3 has helped with the displays connected to the HDMI 2 and HDMI 3 ports.
The HDMI 1 “Alt-Mode” output on the docking station relies on the computer’s internal graphics controller to drive the display and I would expect it to work just like any other USB-C to HDMI adapter or hub and not cause similar behavior.
May I ask you to try this setup to see if the issue is reproduced:
- Connect the Plugable UD-3900PDZ docking station to the computer with displays connected to HDMI 2 and/or HDMI 3 but not to HDMI 1
- Connect the second USB-C to HDMI hub to the second USB-C port on the computer, and connect one display to this hub, it should be detected by the computer
Please let me know if the issue is reproduced when using both the Plugable docking station and the second USB-C to HDMI adapter, or if the issue is not reproduced and we can go from here.