Monitor is not detected

[sdjf]

I am dealing with monitor issues as well, with a quite different scenario, on a totally different system, but it seems to me that the kernel is not seeing the monitor's DisplayLink chip, or it would show in lsusb.

My experience is with a DoubleSight monitor on ArchLInuxArm, which is quite different than your systems, but still, I would expect the monitor to show up, even if it is not attached to the correct driver.

Instead, it is shown as a hub? Possibly it is not getting enough power? Is it plugged in to a hub? Have you seen lsusb output, and especially lsusb -t output, for someone who has gotten this monitor to work on Ubuntu? I bet that in the device tree, DisplayLink will show up.

Also, try lsusb -t on your system without the DisplayLink plugged in - If lsusb -t looks the same, then it is not getting seen by the kernel.

Another possibility is that the device and product ID are not interpreted properly, it should be seen as an I/O device even if it is not claimed by any driver, I believe.

EDIT: Did a bit of googling, did not come up with an answer but it seems important to look at information about "Billboard Devices". There may be power issues, because of how various USB standards work. Also look at Power Delivery issues (abbreviated PD). It may require some sort of docking station to resolve them.